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Abstract:

The attenuation and other optical properties of a medium are exploited to
measure a thickness of the medium between a sensor and a target surface.
Disclosed herein are various mediums, arrangements of hardware, and
processing techniques that can be used to capture these thickness
measurements and obtain dynamic three-dimensional images of the target
surface in a variety of imaging contexts. This includes general
techniques for imaging interior/concave surfaces as well as
exterior/convex surfaces, as well as specific adaptations of these
techniques to imaging ear canals, human dentition, and so forth.

Claims:

1. A method comprising: providing a library of a plurality material types
available for use in a fabrication process, each of the plurality of
material types characterized by elasticity; obtaining static data from an
ear canal of a subject, the static data including a three-dimensional
image of a surface of the ear canal at a predetermined pressure;
obtaining dynamic data from the ear canal of the subject, the dynamic
data including data from the ear canal characterizing changes in a shape
of the ear canal related to at least one of a compliance of the ear canal
to changes in pressurization or a shape change of the ear canal in
response to a musculoskeletal movement of a head of the subject;
calculating a shape for an earpiece based upon the static data; and
calculating a material profile for the earpiece based upon the dynamic
data using one or more of the plurality of material types of the library.

2. The method of claim 1 wherein each of the plurality of material types
is characterized by at least one of a bulk modulus, a modulus of
elasticity, and a compressibility.

3. The method of claim 1 wherein each of the plurality of material types
is characterized by two elastic moduli.

4. The method of claim 1 wherein calculating the shape for the earpiece
includes oversizing the earpiece by a predetermined amount relative to
the ear canal.

5. The method of claim 4 wherein oversizing the earpiece includes varying
the predetermined amount according to the dynamic data.

6. The method of claim 1 wherein each of the plurality of material types
is selected from materials available in a rapid fabrication process.

7. The method of claim 1 further comprising converting the shape and the
material profile into an earpiece design for use by a rapid fabrication
system.

8. A system comprising: a database that stores a library of a plurality
material types available for use in a fabrication process, each of the
plurality of material types characterized by an elasticity; a
three-dimensional imaging system adapted to obtain static data from an
ear canal of a subject, the static data including a three-dimensional
image of a surface of the ear canal at a predetermined pressure, and
further adapted to obtain dynamic data from the ear canal, the dynamic
data including data from the ear canal characterizing changes in a shape
of the ear canal related to at least one of a compliance of the ear canal
to changes in pressurization or a shape change of the ear canal in
response to a musculoskeletal movement of a head of the subject; a
display; and a processor configured to calculate a shape for an earpiece
based upon the static data, and configured to calculate a material
profile for the earpiece based upon the dynamic data using one or more of
the plurality of material types of the library, and further configured to
present the shape and the material profile on the display.

9. The system of claim 8 wherein the processor is further configured to
create a design for the earpiece for export to a rapid fabrication
system.

10. The system of claim 8 further comprising a user interface rendered on
the display that accepts manual revisions to at least one of the shape
and the material profile.

11. The system of claim 8 wherein each of the plurality of material types
is characterized by at least one of a bulk modulus, a modulus of
elasticity, and a compressibility.

12. The system of claim 8 wherein each of the plurality of material types
is characterized by two elastic moduli.

13. The system of claim 8 wherein the processor is configured to
calculate the shape for the earpiece by oversizing the earpiece by a
predetermined amount relative to the ear canal.

14. The system of claim 13 wherein oversizing the earpiece includes
varying the predetermined amount according to the dynamic data.

15. The system of claim 8 wherein the processor is further configured to
convert the shape and the material profile into an earpiece design for
use by a rapid fabrication system.

16. A computer program product embodied on a non-transitory computer
readable medium that, when executing on one or more computing devices,
performs the steps of: accessing a library of a plurality material types
available for use in a fabrication process, each of the plurality of
material types characterized by an elasticity; obtaining static data from
an ear canal of a subject, the static data including a three-dimensional
image of a surface of the ear canal at a predetermined pressure;
obtaining dynamic data from the ear canal of the subject, the dynamic
data including three-dimensional data from the ear canal characterizing
changes in a shape of the ear canal related to at least one of a
compliance of the ear canal to changes in pressurization or a shape
change of the ear canal in response to a musculoskeletal movement of a
head of the subject; calculating a shape for an earpiece based upon the
static data; and calculating a material profile for the earpiece based
upon the dynamic data using one or more of the plurality of material
types of the library.

17. The computer program product of claim 16 wherein each of the
plurality of material types is characterized by at least one of a bulk
modulus, a modulus of elasticity, and a compressibility.

18. The computer program product of claim 16 wherein each of the
plurality of material types is characterized by two elastic moduli.

19. The computer program product of claim 16 wherein calculating the
shape for the earpiece includes oversizing the earpiece by a
predetermined amount relative to the ear canal.

20. The computer program product of claim 19 wherein oversizing the
earpiece includes varying the predetermined amount according to the
dynamic data.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser.
No. 13/169,972 filed Jun. 27, 2011, which is a continuation-in-part of
U.S. patent application Ser. No. 12/508,804 filed Jul. 24, 2009 now U.S.
Pat. No. 8,107,086 issued on Jan. 31, 2012, which claims the benefit U.S.
Provisional Patent Applications No. 61/083,394 filed on Jul. 24, 2008 and
U.S. Provisional Patent Application No. 61/165,708 filed on Apr. 1, 2009,
each of which is hereby incorporated by reference in its entirety.

[0003] While these existing techniques provide a useful approach for
obtaining thickness measurements, they rely on various mixtures of two or
more fluorescent dyes. There remains a need for other thickness
measurement techniques that do not require the use of multiple dyes, as
well as techniques for adapting thickness measurements to various
physical contexts for three-dimensional imaging.

SUMMARY

[0004] The attenuation and other optical properties of a medium are
exploited to measure a thickness of the medium between a sensor and a
target surface. Disclosed herein are various mediums, arrangements of
hardware, and processing techniques that can be used to capture these
thickness measurements and obtain dynamic three-dimensional images of the
target surface in a variety of imaging contexts. This includes general
techniques for imaging interior/concave surfaces as well as
exterior/convex surfaces, as well as specific adaptations of these
techniques to imaging ear canals, human dentition, and so forth.

BRIEF DESCRIPTION OF THE FIGURES

[0005] The invention and the following detailed description of certain
embodiments thereof may be understood by reference to the following
figures:

[0025] FIG. 20 is a flowchart of a method 2000 for earpiece selection
using dynamic data.

[0026] FIG. 21 is a flowchart of a method 2100 for creating a material
profile to fabricate an earpiece.

[0027] FIG. 22 is a flowchart of a method for simulation of dynamic fit
and acoustics for an earpiece.

[0028] FIG. 23 is a flowchart of a method for positioning control inputs
in an earpiece.

[0029] FIG. 24 shows an earpiece designed according to the method of FIG.
23.

[0030] FIG. 25 is a flowchart of a method for using dynamic ear canal data
for medical diagnosis.

[0031] FIG. 26 is a flowchart of a method for fitting an earpiece using
dynamic data.

DETAILED DESCRIPTION

[0032] Disclosed herein are various techniques for obtaining thickness
measurements from a film, liquid, gel, gas, or other medium based upon
the relationship between an intensity of light measured at two or more
different wavelengths. Also disclosed herein are various techniques for
capturing such thickness measurements in interior volumes (such as ear
canals), exterior volumes (such as teeth), and so forth for use in
three-dimensional reconstruction. In general, the systems and methods
described below exploit the Beer-Lambert Law for absorption of light in a
medium, and more particularly, derivations based upon the Beer-Lambert
Law where one wavelength is attenuated more than another as it passes
through a medium. By controlling sources of light and the properties of
the medium, this differential attenuation can be used to determine a
distance that light travels through a medium to a sensor. More specific
applications of this general principle are provided below, and serve to
outline several variations of a new technique for distance measurement
based upon differential attenuation of various wavelengths of light.

[0033] Throughout this disclosure, the term "absorption" is used to
describe an attenuation of energy such as electromagnetic energy
propagating through a medium. This attenuation may be caused by physical
absorption in the medium, or by any other physical phenomenon (such as
scattering) or combination of phenomena that result in a measurable
decrease in intensity of a signal as it passes through the medium. For
example, it will be understood that in some embodiments--such as those
involving gold nanoparticles as described herein--"absorption" is the
result of multiple inelastic scattering events. Thus as used herein
absorption should be understood broadly to refer to any form or cause of
attenuation (or lack thereof) unless a more specific meaning is
explicitly provided or otherwise clear from the context.

[0034] In the following description, terms such as thickness, thickness
calculation, and thickness measurement are used interchangeably to
describe the thicknesses as determined using the techniques disclosed
herein. In general, no particular meaning should be ascribed to the terms
"measurement" and "calculation", and the use of one term or the other, or
similar references to "determining", "calculating", or "obtaining"
thickness measurement, is not intended to imply any distinction among the
manners in which thickness might be determined. Rather, all such
references to thickness should be understood to include all of the
techniques described herein for determining thickness of a medium or the
length of an optical path therethrough, except where a more specific
meaning is explicitly provided.

[0035] Throughout this disclosure, various terms of quantitative and
qualitative description are used. These terms are not intended to assert
strict numerical boundaries on the features described, but rather should
be interpreted to permit some variability. Thus for example where medium
is described as being transparent at a particular wavelength, this should
be understood to mean substantially transparent or sufficiently
transparent to permit measurements yielding accurate thickness
calculations, rather than absolutely transparent at the limits of
measurement or human perception. Similarly, where a target surface is
described as having uniform color or a dye is described as fluorescing at
a particular wavelength, this should not be interpreted to exclude the
variability typical of any conventional material or manufacturing
process. Thus in the following description, all descriptive terms and
numerical values should be interpreted as broadly as the nature of the
invention permits, and will be understood by one of ordinary skill in the
art to contemplate a range of variability consistent with proper
operation of the inventive concepts disclosed herein, unless a different
meaning is explicitly provided or otherwise clear from the context.

[0036] In the following description, the term wavelength is used to
describe a characteristic of light or other electromagnetic energy. It
will be understood that the term wavelength may refer to a specific
wavelength, such as where the description refers to a center frequency or
a limit or boundary for a range of frequencies. The term may also or
instead refer generally to a band of wavelengths, such as where a
wavelength is specified for a sensor, pixel, or the like. Thus in general
the term wavelength as used herein should be understood to refer to
either or both of a specific wavelength and a range of wavelengths unless
a more specific meaning is provided or otherwise clear from the context.

[0037] All documents mentioned herein are hereby incorporated by reference
in their entirety. References to items in the singular should be
understood to include items in the plural, and vice versa, unless
explicitly stated otherwise or clear from the text. Grammatical
conjunctions are intended to express any and all disjunctive and
conjunctive combinations of conjoined clauses, sentences, words, and the
like, unless otherwise stated or clear from the context.

[0038] Although the following disclosure includes example embodiments,
these examples are provided for illustration only and are not intended in
a limiting sense. All variations, modifications, extensions,
applications, combinations of components, and the like as would be
apparent to one of ordinary skill in the art are intended to fall within
the scope of this disclosure.

[0039] FIG. 1 shows a three-dimensional imaging system. In an embodiment,
the system 100 may employ a fluorescent medium between an object and a
camera, although it will be readily appreciated that a variety of
mediums, sensors, and other components may be used. The system 100 may
include an excitation source 102 with a source filter 104, a medium 106,
an object 108 with a target surface 110, a sensor 112 with a sensor
filter 114, and a computer 116. In general operation, the excitation
source 102 illuminates the object 108 along an optical illumination path
118 through the medium 106, and the sensor 112 captures reflected light
from the object 108 on an optical return path 120 through the medium 106.
The resulting signal at the sensor 112 can be processed by the computer
116 to obtain thickness measurements of the medium 106, which can be
further processed to obtain a three-dimensional image of the object 108.
It will be understood that numerous variations, additions, omissions, and
modifications are possible, all as described in the various detailed
embodiments set out below.

[0040] The excitation source 102 may be any suitable light source. In
various embodiments, this may include light emitting diodes, incandescent
bulbs or lamps, laser light sources, or any other broadband light source,
broadband visible light source, narrowband light source or any
combination of the foregoing that emits photons at the desired
wavelength(s). The excitation source 102 (as shaped by the source filter
104) may provide light at any suitable wavelength(s) including
wavelengths that excite a fluorescent substance in the medium 106 or on
the target surface 110, as well as wavelength(s) having known attenuation
by the medium 106, all as more generally described below. The excitation
source 102 may more generally include any source of illumination suitable
for imaging as described herein. While visible light embraces one useful
range of wavelengths, the excitation source 102 may also or instead
usefully provide light near or beyond the visible light range such as
near-infrared or infrared illumination, or more generally across any
range of electromagnetic wavelengths for which attenuation by the medium
106 can be measured. Various other embodiments are discussed in greater
detail below, and it will be appreciated that the term "excitation
source" as used herein should be broadly understood as any source of
energy capable of achieving illumination of the object 108. In one
embodiment, the excitation source 102 may be a light source positioned to
excite a single fluorescent substance around the object 108 (e.g., within
the medium 106) to provide a fluorescent emission, or more generally to
illuminate the medium 106 and/or target surface 110 as required to
capture suitable intensity measurements at the sensor 112 for thickness
calculations as described below.

[0041] One or more source filters 104 may optionally be employed to shape
a spectral profile of the excitation source 102, such as to provide
narrowband illumination from a broadband light source, or to otherwise
attenuate energy outside wavelengths of interest. For example, where the
sensor 112 captures a fluorescent or other radiant image from the object
108, the one or more source filters 104 may usefully remove or attenuate
the fluorescence wavelength(s) from the excitation source 102 in order to
avoid contamination of fluorescence images.

[0042] The medium 106 may include any substance, mixture, solution,
composition or the like suitable for the imaging systems and methods
described herein. In general, the medium 106 may have known and different
coefficients of attenuation for two different wavelengths so that a ratio
of intensity at these wavelengths can be captured and used in thickness
calculations. The medium 106 may also include a single fluorescent,
phosphorescent, or similarly radiant substance that contributes to the
intensity of electromagnetic energy at one of the two different
wavelengths. In embodiments, one of the attenuation coefficients is zero.
In embodiments, one of the attenuation coefficients is greater than or
less than the other, or to improve discrimination in a calculation
including a ratio, significantly greater than or less than the other.

[0043] In one aspect, the medium 106 may be selected for its mechanical
properties. Thus, the medium 106 may include one or more of a liquid, a
gas, a solid, a gel, or other substance or combination of substances. For
example, a liquid such as a silicon oil may be conveniently employed
where the object 108 is small and can be fit into a bath or other
container with the oil. As another example, a gas with a fluorescent dye
may be usefully employed in an interior space as described in various
embodiments below. In other embodiments, the medium 106 may be a casting
medium such as a curable gel into which the object 108 may be pressed and
removed leaving a negative impression of the object in the medium 106. In
various embodiments, such a curable material may be cured while the
object 108 is in the medium 106, after the object 108 has been removed
from the medium 106, or some combination of these. The medium 106 may
cure with the passage of time, or with the application of heat, light,
pressure, or the like, or through some other activation medium.

[0044] In another aspect, the medium 106 may be selected for its optical
properties such as luminescence (e.g., fluorescence) and/or attenuation.
Thus the medium 106 may in general be transparent across some portion of
the electromagnetic spectrum so that light passing through the medium 106
in some wavelengths is not attenuated. The medium 106 may also have a
non-zero coefficient of attenuation at some wavelengths so that light at
these wavelengths is attenuated as it passes through the medium 106. This
may be achieved, for example, through the use of an additive such as gold
nanoparticles (which can be very closely tuned to achieve attenuation at
specific, narrow bands of wavelengths) or any other substance or
combination of substances that achieves a desired attenuation spectral
profile. The medium 106 may also contain fluorescent dyes, phosphorescent
dyes, quantum dots, or some other substance or combination of substances
that emits light in response to other wavelengths or other stimulus (such
as an applied electrical field, a chemical reaction, and so forth). In
such embodiments, the intensity of the emitted light may be used to
assist calculations of a thickness of the medium 106, as described in
greater detail below. The medium 106 may also or instead include any
chemiluminescent material, electroluminescent material, or other material
that emits light at one or more measurable wavelengths.

[0045] Thus, the medium 106 may in general include a variety of dyes,
solutes, quantum dots, encapsulated silica nanoparticles, or other
substances that can be combined--such as in a homogenous mixture--to
provide the medium 106 with different emission properties and/or
attenuation coefficients at different wavelengths. The medium 106,
including additives, may be formed of biocompatible materials so that it
is safe for use on, in, or in close proximity to a living organism. One
useful biocompatible dye is fluorescein sodium, although it will be
appreciated that a variety of biocompatible fluorescent dyes are known
and may be usefully employed with the systems and methods described
herein.

[0046] The object 108 may be any object having a target surface 110 from
which a three-dimensional image is to be acquired. This may include, for
example biological or physiological subject matter such as teeth (or a
cast of teeth), bones, hands, fingerprints, or more generally any tissue,
skeleton, organs, and the like including without limitation interior
surfaces such as an ear canal, nasal passage, bladder, and so forth. This
may also, or instead, include fabricated items such as precision-machined
components, precision cast parts, fuel injectors, turbine blades, seals,
or any other three-dimensional object where quality control may usefully
include an evaluation of three-dimensional shape. This may also, or
instead, include models that can be usefully digitized for subsequent
computerized processes such as computer-automated design, computer
animation, and so forth. More generally, the object 108 may be any object
from which a three-dimensional image can be usefully captured.

[0047] The sensor 112 may include any sensor or group of sensors suitable
for capturing, in digital or electronic form, an intensity of
electromagnetic radiation at one or more wavelengths. This may include,
for example, photodiodes, charge-coupled devices (CCDs), complementary
metal oxide semiconductor (CMOS) devices, or any other optical sensor or
combination of sensors suitable for use with the systems and methods
described herein. In general, the sensor 112 may be positioned to measure
an intensity of one or more wavelengths of light in a direction of a
location within a region of interest on the target surface 110, such as
indicated where the optical return path 120 leaves the object toward the
sensor 112 and sensor filter 114.

[0048] The sensor 112 may include a two-dimensional pixel array that can
capture a two-dimensional image in which a measurement at each pixel
location corresponds to an intensity of one or more wavelengths of light
in a direction within a field of view of the sensor 112. This may, for
example, include conventional CCD arrays, such as a grayscale array, a
red-green-blue (RGB) array, a cyan-magenta-yellow (CMY) array, or the
like. Various techniques are known for discriminating different
wavelengths including filter masks overlaying a detector to capture a
particular range of wavelengths at each pixel location, a filter wheel
with which time-separated (and wavelength-separated) images can be
captured through each of a sequence of filters, or a prism that separates
an optical path into three sub-paths each used to measure a different
wavelength. In other embodiments, nested semiconductor wells or the like
may be employed to measure different wavelengths at different depths
within the semiconductor device. Although not separately illustrated, it
will be appreciated that the sensor 112 may include a variety of camera
optics such as focusing lenses, zoom lenses, prisms, mirrors, and so
forth, as well as other camera hardware such as shutters, aperture
controls, and so forth, any of which may be custom built for a particular
imaging environment or integrated into a commercially-available camera or
some combination of these.

[0049] In general, the techniques described herein use two measured
wavelengths. However, it should be appreciated that additional
wavelengths may be usefully employed to increase accuracy or to
accommodate use with a range of different mediums 106. The measured
wavelengths may be at or near specific wavelengths detected by
conventional camera hardware, or at other wavelengths, and may in general
include ranges or bands of varying size around certain center wavelengths
according to the sensitivity of the sensors that are used and/or the
properties of the excitation source 102 and the medium 106. In some
embodiments the measured wavelengths are 510 nanometers and 540
nanometers, respectively.

[0050] The sensor filter 114 may be any filter or combination of filters
useful for selectively passing one or more wavelengths of light to the
sensor 112, including the filter masks described above for discriminating
wavelengths at the sensor, or one or more filters separate from the
sensor 112 for gross filtering of an incoming optical signal, such as to
attenuate light outside one or more wavelengths of interest. In various
embodiments the sensor filter 114 may include a switchable optical
bandpass filter, an optical bandpass filter, a color filter, a
stray-light filter that attenuates all light outside of the measured
wavelengths, an excitation filter that attenuates over the excitation
bands, and so on.

[0051] The computer 116 may include any suitable computing device or
devices including without limitation a desktop computer, laptop computer,
or dedicated processing device(s). The computer may include one or more
general purpose or special purpose processors constructed and/or
programmed to receive measurements of intensities, perform calculations
to determine the thickness of an attenuation medium, and output results
of the calculations as described herein. This may include the use of
software, firmware, microcode, programmable gate arrays, application
specific circuits, and so on. In general, the computer 116 may provide
one or more high-level functions as described below.

[0052] In one aspect, the computer 116 may control operation of the
excitation source 102 and sensor 112 to obtain sensor images of the
object 108. This may include supplemental functions such as controlling a
supply of the medium 106 or otherwise providing monitoring and control of
hardware for the systems and methods described herein. In another aspect,
the computer may obtain data from the sensor 112, such as a
two-dimensional array of intensity values captured from a field of view
that contains the object 108 and the medium 106. This may include
intermediate processing such as controlling operation of the sensor 112
or a data feed from the sensor 112, as well as processing digital
measurements from the sensor 112 to obtain intensity values at particular
wavelengths of interest. Thus, for example, where an RGB camera is
employed, the computer 116 may receive three discrete wavelength
measurements for each pixel of the camera (e.g., a red wavelength, a
green wavelength, and a blue wavelength) and process these RGB values at
each pixel location to determine or estimate an intensity at one or more
wavelengths between the discrete RGB values for use in subsequent
calculations.

[0053] In another aspect, the computer 116 may calculate a thickness of
the medium 106 in a direction of a location on the object 108 (e.g.,
along the optical return path 120 to a particular sensor/pixel location)
based upon a function of the intensity at two or more specific
wavelengths. In general, each sensor 112 (or pixel location within a
sensor 112) provides a measurement of intensity at two different
wavelengths in the direction of a location on the target surface 110,
which may correspond to a general area of interest, or a particular
location within a region of interest depending on the optical resolution
of the sensor 112 and related hardware.

[0054] Where the medium 106 has a different attenuation coefficient at
each of two measured wavelengths and the medium 106 fluoresces or
otherwise radiates at one of these two wavelengths, the intensity at each
of the two wavelengths can be related to a thickness of the medium 106 in
the direction of the location. Suitable adaptations may be made where,
for example, the medium 106 contains a fluorescent dye that is excited by
the excitation source 102, or where the medium 106 contains two
fluorescent dyes that are excited by the excitation source 102, or where
the medium 106 has known attenuation coefficients and the target surface
110 has a known color pattern, or where the target surface 110 has a
luminescent surface that luminesces at a wavelength that is attenuated by
the medium 106. In some embodiments, a baseline image of the target
surface 110 (e.g., taken without the medium 106 present) may be used to
obtain the known color pattern. Preferably, the non-absorbing medium and
the medium 106 have similar indices of refraction (i.e., they are index
matched), so that the baseline image and any images taken with the medium
106 line up as exactly as possible. Translation, rotation, warping, and
the like may also be employed to adapt a baseline image to various
perspectives on an object, such as where a camera or other sensor obtains
images from a variety of poses that are used to form a composite
three-dimensional image. However adapted, this general notion may be
employed to obtain a number of thickness measurements in the direction of
a corresponding number of locations on the target surface 110

[0055] In another aspect, the computer 116 may process thickness
measurements to obtain a three-dimensional reconstruction of the target
surface 110. With a number of simple constraints such as information
about the physical boundaries of the medium 106, the directionality
associated with pixel or other sensor measurements, and a straightforward
application of Euclidean geometry, thickness measurements can be
transformed into a three-dimensional data set representing the target
surface 110. This three-dimensional data can be stored, displayed, output
to another computer process, and so forth. It will be understood that
while the medium 106 is depicted in FIG. 1 as having a generally
rectangular cross section, this is not strictly required and any shape of
medium 106 may be employed provided that enough information about the
surface of the medium is available to permit inferences about the target
surface based on thickness measurements. For example, a lens of the
sensor 112 may be immersed in the attenuation medium, such that thickness
measurements are made directly from a surface of the lens to the object
108. In another aspect, the object 108 may be immersed in a bath of the
medium 106 where a top surface of the bath has a known position such that
thickness can be projected (based upon directionality) from this surface
to the target surface.

[0056] This process may be supplemented in a number of ways. For example,
a three-dimensional video may be created with a series of time-separated
measurements. In another aspect, the sensor 112 or the object 108 may be
moved (in a translation, a rotation, or some combination of these) in
order to capture a larger area of interest or the entire object 108, or
in order to obtain measurements of occluded surfaces of the object 108,
or for any other reason. In such a motion-based imaging process, the
relative positions of the sensor 112, the object 108, and/or the medium
106 may be physically tracked with motion sensors or the like, or the
relative motion may be inferred using a three-dimensional registration
process to spatially relate successive three-dimensional data sets to one
another. Regardless of the particular methodology, it will be readily
appreciated that individual spatial measurements, or groups of spatial
measurements, may be combined to form a larger three-dimensional model,
and all such techniques that would be apparent to one of ordinary skill
in the art for creating a three-dimensional reconstruction are intended
to fall within the scope of this disclosure.

[0057] In another aspect, the computer 116 may provide a user interface
for control and operation of the system 100, as well as tools for
displaying thickness measurements, displaying or manipulating
reconstructed three-dimensional models, and so forth.

[0058] The computer 116 may also support calibration of the system 100 in
order to correct for, e.g., variations in the sensor 112, the excitation
source 102, and related optics, or variations in concentration of
additives to the medium that absorb, scatter, attenuate, fluoresce, or
otherwise impart various optical properties to the medium. For example
and without limitation, it will be understood that one can characterize
the sensor 112 using a calibration fixture or the like, prior to
employing the sensor 112 in the system 100. Additionally, it will be
understood that by taking controlled measurements of the absorption
spectrum or the emission spectrum for the medium 106 it may be possible
to improve the accuracy of the thickness measurements and related
calculations. Calibration may, for example, include the use of an object
108 having a known shape and a known position within the medium 106, or
the use of a container for the medium having a known shape. A variety of
suitable calibration techniques will be readily appreciated based upon
the use of known shapes, dimensions, surface patterns, and so forth, any
of which may be adapted to use with the imaging systems described herein.

[0059] A supply 122 of the medium 106 may be provided and adapted to
distribute the medium 106 between the sensor 112 and the target surface
110. It will be understood that, while the supply 122 is depicted as an
external reservoir, the supply should more broadly be understood as any
structures that deliver the medium 106 and/or retains the medium 106
about the object 108 in a manner that permits thickness measurements
including any pumps, valves, containers, drains, tubing, and the like
consistent with supplying the medium 106 for the uses described herein.

[0060] FIG. 2 shows the emission and absorption spectra for fluorescein
sodium. In general, the imaging techniques described above may employ
known ERLIF techniques using two different fluorescent dyes. However, in
one aspect the imaging system may instead be implemented using a medium
that contains a single fluorescent dye (or other substance) such as
fluorescein sodium that has an absorption spectrum 202 that overlaps with
an emission spectrum 204. By exciting this dye with a blue light and
capturing fluorescent image pairs in ten nanometer bands within the
overlapping spectrum 206 of non-zero absorption and attenuation, such as
centered on about 510 nanometers and about 540 nanometers, intensity
values can be obtained for thickness calculations in a manner similar to
the ERLIF techniques noted above. Thus in one embodiment there is
disclosed herein a thickness measurement and/or three-dimensional imaging
system that uses a medium with a single fluorescent dye, wherein the dye
has overlapping, non-zero emission and absorption spectra.

[0061] FIG. 3 shows a three-dimensional imaging system using a luminescent
surface applied to an object. In general, the system 300 may be as
described above with reference to FIG. 1 with differences as noted below.
A luminescent layer 322 may be applied to the target surface 110 of the
object 108, and may emit light at a first wavelength and a second
wavelength that can be measured by the sensor 112 in order to facilitate
calculations of thickness of the medium 106. In general, the sensor 112
may be positioned to capture an intensity of the first wavelength and the
second wavelength in a direction of a location on the target surface 110,
and a processor such as the computer 116 may be programmed to calculate a
thickness of the medium in the direction of the location based upon a
function of the intensity of the first and second wavelengths.

[0062] In one aspect, a luminescent layer 322 is applied to the target
surface 110 or embedded within the object 108 (such as using a waveguide
or the like). Emissions from the luminescent layer 322 may travel along
the optical return path 120 as described above. Although the following
description refers explicitly to a layer of luminescent material, it will
be readily understood that the object 108 may also or instead be
fabricated from a luminescent material to achieve a similar effect, or
may contain waveguides or the like that luminesce. Thus as used herein
the term "luminescent layer" should not be interpreted as requiring a
discrete layer of luminescent material on the target surface 110 of the
object 108. Rather any technique for rendering the object 108 luminescent
should be understood as creating the luminescent layer 322 as that term
is used herein unless a different meaning is explicitly stated or
otherwise clear from the context. In general, the luminescent layer 322
may be formed of any suitable combination of materials selected for
appropriate mechanical properties, optical properties, and other
properties.

[0063] Mechanical properties of the luminescent layer 322 may depend on
the manner in which the luminescent layer 322 is to be applied. For
example, an oil or other relatively viscous material may be appropriate
for dip coating the object 108, while a less viscous fluid might be
usefully employed for spraying or painting onto the target surface 110.
In other embodiments, a thin film or other membrane may be impregnated
with a luminescent material (or fabricated from a luminescent material,
or coated with a luminescent material) and be used to form the
luminescent layer 322 in an inflatable membrane as described below. The
membrane may be elastic, deformable, flexible, pliable, or any
combination of these, or have any other properties useful for forming a
conforming, luminescent layer over the object 108.

[0064] In embodiments, the luminescent layer 322 may be a membrane that
can be wrapped around some or all of the object 108. The object 108,
enclosed in the luminescent layer 322 may then be introduced into the
medium 106 and thickness measurements may be obtained from any number of
poses from within or outside of the medium 106. Thus for example, where
the object 108 is a human foot, a sock may be fashioned of a material
with the luminescent layer 322 disposed on an outside of the sock. A foot
may then be inserted into the sock, which may in turn be placed into the
medium 106 to obtain a three-dimensional model of the foot. This approach
may more generally be employed to obtain three-dimensional images using a
membrane such as any of the elastic or inelastic membranes described
herein as an exterior enclosure for a target surface. Thus in one
embodiment there is disclosed herein a sock (or other enclosing membrane)
with a luminescent exterior surface, which may be used for capturing
three-dimensional images of an object inserted into the sock.

[0065] Optical properties of the luminescent layer 322 may be controlled
by the introduction of suitable additives. The luminescent layer 322 may
include a fluorescent dye or other radiant substance that responds to
illumination from the excitation source 102. One suitable fluorescent
substance may include coumarin-153, which is a powder that can dissolve
and/or spread very well in certain plastics, has suitable fluorescent
properties, and appears to be non-toxic. In another aspect, the
luminescent layer 322 may contain a chemiluminescent or
electroluminescent material that serves as a direct source of light.
Suitable chemiluminescent materials may include a solution with hydrogen
peroxide in the presence of a catalyst (e.g., iron or copper), cyalume in
a solution with hydrogen peroxide in the presence of a catalyst (e.g.,
sodium salicylate), and so on. It will be appreciated that a variety of
liquid-phase and gas-phase chemiluminescent compositions of matter may be
employed. Suitable electroluminescent materials may, for example include
powder zinc sulfide doped with copper or silver, thin film zinc sulfide
doped with manganese, and so on. More generally, a variety of
chemiluminescent and electroluminescent materials are known and may be
adapted to use as a luminescent layer 322 as described herein. Thus, the
luminescent layer 322 may include a chemiluminescent layer, an
electroluminescent layer, a fluorescent layer, or some combination of
these.

[0066] In alternate embodiments, the luminescent layer 322 may include an
optical waveguide on the target surface 110 or within the object 108. It
will be understood that a variety of geometries, mode structures, and
materials for the optical waveguide are possible and may be adapted to
use with the systems described herein.

[0067] The excitation source 102 may provide one or more wavelengths of
light to excite a fluorescent dye or the like within the luminescent
layer 322. In other embodiments, the excitation source 102 may be
entirely omitted, or may be alternatively realized as a chemical,
electrical, or other source of energy that produces illumination from the
luminescent layer 322. In embodiments, the excitation source 102 may
include an electrical power source that directly powers a waveguide in
the object 108. In other embodiments, the excitation source 102 may
include an electrical field, chemical precursor, or other means for
illuminating the luminescent layer 322.

[0068] Thus it will be appreciated that the luminescent layer 322 may be
formed of a variety of different carriers and additives. In embodiments,
the luminescent layer 322 may contain any suitable luminescent pigment,
such as a fluorescent dye in a liquid carrier that can be sprayed or
painted onto the object 108, or a film or membrane that is coated or
impregnated with a fluorescent material. For in vivo imaging, the
luminescent layer 322 may be formed of biocompatible substances. In
embodiments, the luminescent layer 322 may include biocompatible
fluorescent metal oxide nanoparticles (and coatings containing same),
thin film flexible electroluminescent sources, or nanoparticles with a
surface coating of chemiluminescent molecules.

[0069] In embodiments with a luminescent layer 322, suitable intensity
measurements may be obtained for thickness calculations based upon
relative attenuation of different wavelengths without the need for a
fluorescent or otherwise luminescent medium 106. In order to achieve
desired attenuation properties, the medium 106 may include a carrier
formed of a transparent fluid in which gold nanoparticles or nanorods are
uniformly distributed. Gold nanoparticles or nanorods have an absorption
profile that can be tuned based on the size and shape of the
nanoparticles or nanorods themselves. In embodiments, the gold
nanoparticles or nanorods can be tuned to absorb more optical energy
within a predetermined band of visible light wavelengths than at other
wavelengths. The gold nanoparticles or nanorods may have a concentration
within the carrier such that the medium 106 is transparent (i.e.,
maintains substantially zero attenuation) outside of the predetermined
band.

[0070] It will be appreciated that disclosed herein are various means for
performing the functions associated with the use of the luminescent layer
322. An applying means for applying the luminescent layer 322 to the
target surface 110 may include, for example, a paint brush, a sprayer, an
atomizer, or a bath of material for the luminescent layer 322 into which
the target surface 110 may be dipped. A distributing means may include a
supply of the medium as well as any structures for retaining the medium
in a desired area around the object such as a container with side wall
for a liquid, or a gas-tight chamber for retaining the medium in a
gaseous form. Sensor means may include any of the sensors described
herein. A processing means may include any of the computing devices or
other processing hardware described herein.

[0071]FIG. 4 shows a three-dimensional imaging system using a passive
optical layer applied to an object. In general, the system 400 is as
previously described with differences as noted below. A passive layer 422
may be applied to the target surface 110 of the object 108 in order to
impart the object 108 with known optical properties that can be used in
combination with an attenuating medium 106 to determine thickness based
upon measurements of intensity at various wavelengths.

[0072] The medium 106 may be any one or more of the attenuating media
described above that provide different attenuation coefficients for at
least two different wavelengths. The excitation source 102 may be a
broadband light source that provides illumination of the object 108 over
a range of wavelengths (or ranges of wavelengths) that includes the at
least two different wavelengths used for thickness calculations.

[0073] In general, the passive layer 422 may be constructed using any of
the techniques described above for a luminescent layer 322. This includes
spraying, painting, or otherwise applying the passive layer 422 to the
object 108, or fabricating the object 108 with an exterior surface having
the desired properties. In general, the passive layer 422 imparts a known
optical pattern onto the object 108 so that the object 108 has a
predetermined color over a region of interest. The predetermined color
may be a uniform color that is unknown, a uniform color that is a known
(e.g., a specific color), or a known color distribution.

[0074] In operation, the object 108 may be illuminated by the excitation
source 102, and an intensity at the at least two wavelengths may be
measured by the sensor 112. By using a broadband light source and a known
color distribution on the object 108, the ratio of reflected intensities
can be assumed to be constant across the target surface 110. Thus any
variation in the ratio of measured intensities can be correlated to a
thickness of the attenuating medium 106 and a thickness can be
calculated. Using a ratio may also reduce the effects on thickness
calculations of any spatial non-uniformity in the illumination source or
in the reflectivity of the passive layer.

[0075] In one aspect, the passive layer 422 may have a color that varies.
This may be useful, for example, where the target surface 110 is expected
to exhibit significant variability in height (with corresponding
variability in thickness of the medium 106). In general, the sensitivity
of measured intensities of light at the sensor 112 to the thickness of
the medium 106 may depend on a number of factors including a color
selected for the passive layer 422. Where a surface is expected to be
nearly planar, high sensitivity may be preferred in order to achieve
greater resolution in thickness measurements. However, where a surface is
expected to be highly non-planar, lower sensitivity may be required in
order to avoid saturation of the sensor 112, or more generally to provide
an adequate depth of field to capture depth. Where some information is
available a priori concerning the shape of the object 108 being measured,
this information can be used to scale measurement resolution accordingly
with a suitable, corresponding selection of color on the target surface
110.

[0076] The passive layer 422 may also or instead have other properties
selected to assist in capturing accurate thickness measurements. For
example, a matte finish may provide more consistent reflective properties
for the target surface 110 across a range of illumination conditions.
Similarly, a dark color finish may absorb certain wavelengths of incident
light that would otherwise interfere with sensor measurements.

[0077] In one aspect, a system described herein for capturing thickness
measurements from a target surface with a known color distribution may
include a distributing means, which may be the supply 122 or any of the
other means described above for distributing a medium between a target
surface and a sensor or retaining the medium in this distribution. The
system may include an illuminating means which may be any of the light
sources or other excitation sources described above. The system may
include a sensor means which may include any of the sensors described
above suitable for capturing wavelength intensity data corresponding to
the illumination provided by the illumination means. Finally, the system
may include a processing means which may include any processor or
computing device described herein programmed to calculate thickness based
on wavelength intensity measurements and, where appropriate, to further
reconstruct a three-dimensional image from the resulting thickness(es).

[0078] In one aspect, the systems described above advantageously permit
three-dimensional imaging using a single camera such as a conventional
color camera. By physically arranging a medium, illumination sources,
and/or surface treatment of an object according to the various
embodiments described above, thickness measurements can be obtained with
a single camera and geometrically converted into a three-dimensional
image of a target surface. Thus, in one aspect a three-dimensional
imaging device disclosed herein includes a camera and a processor. The
camera, which may be a conventional color camera, may include a lens and
one or more sensors capable of capturing a two-dimensional color image of
a field of view including an intensity at a first wavelength and a second
wavelength, which may be any of the wavelengths or bands of wavelengths
described above. The intensity at each pixel location in the
two-dimensional image corresponds to a direction from the lens into the
field of view so that suitable directionality for the measurement can be
inferred and employed in a three-dimensional reconstruction. The
processor, which may be the computer or any other processing devices
described above, may then calculate a thickness of a medium in the
direction corresponding to each one of the plurality of pixel locations
as a function of the intensity of the first wavelength and the intensity
of the second wavelength at that one of the plurality of pixel locations,
thereby providing a plurality of thickness measurements. From this
plurality of thickness measurements and related information such as the
directionality associated with each pixel and any a priori information
about the geometric boundaries of the medium, the processor may calculate
a three-dimensional image of an object within the field of view.

[0079] It should be appreciated that the presently disclosed use of a
single camera in obtaining a three-dimensional image can be applied in
the context of conventional ERLIF technique as well.

[0080] For sensors 112, the camera may include a complementary metal oxide
semiconductor (CMOS) chip camera with one or more CMOS sensors in a solid
state device, or the camera may include an array of charge-coupled
devices in a solid state device. The camera may include any number of
filters to selectively capture the intensity of the first and second
wavelengths at each one of the plurality of pixel locations. The filters
may include a filter mask disposed on the imaging device (i.e.,
integrated into the camera chip or other solid state imaging device). For
example, the camera may include a plurality of filters for selectively
capturing an intensity of different wavelengths at different ones of the
plurality of pixel locations, such as a conventional RGB or CMY filter
mask, or a plurality of filters to selectively capture specific
wavelengths used in thickness calculations. The filters may also or
instead include external filter devices or systems, and may include
active filters that permit adjustments to filter properties during
operation or fixed filters such as dichroic mirrors or the like manually
positioned in front of a camera lens.

[0081] The camera may capture RGB (red, green, blue) or CMY (cyan,
magenta, yellow) color images as typically found in
commercially-available hardware, or any other useful narrow or broad
ranges of wavelengths. In one embodiment where the medium is a gas, the
camera may be immersed in the gas along with the target surface and the
thickness measurement may be an entire distance from the camera lens to a
location on the surface of the object. A light source or other excitation
source may also be included, all as generally described above, and the
light source may include any filter or combination of filters suitable
for a particular medium. Such filters may be useful, for example, to
selectively pass one or more wavelengths to excite a fluorescent
material, or to attenuate light in wavelengths where fluorescent light is
emitted so as to avoid interference with fluorescent emissions from the
target surface or the intervening medium.

[0082] In another aspect, useful mediums are disclosed for use with the
imaging systems described above. In general, these mediums include any
combination of carriers and other substances (for attenuation or for
fluorescence) devised specifically for use with the systems above and not
otherwise commercially available or described in the art.

[0083] For example, in one aspect, a composition of matter described
herein includes a carrier formed of a transparent fluid medium and a
plurality of gold nanoparticles uniformly distributed within the carrier.
The gold nanoparticles may be advantageously tuned to absorb optical
energy within a predetermined band of visible light wavelengths in order
to facilitate thickness measurements and three-dimensional imaging as
described herein.

[0084] The plurality of gold nanoparticles may be tuned using a shape of
the plurality of gold nanoparticles and/or the plurality of gold
nanoparticles may be tuned using a size of the plurality of gold
nanoparticles. The plurality of gold nanoparticles may have a
concentration within the carrier such that the composition has zero
attenuation outside the predetermined band. The predetermined band may be
between 450 nanometers and 550 nanometers. The carrier may be one or more
of an oil, a gel, a gas, and a liquid, any of which might usefully be
selected according to the subject matter being imaged and the imaging
technique being employed. In one aspect, the carrier may include a
silicon oil. In another aspect where the subject matter can be cast, or a
gel might otherwise serve as a useful medium, the carrier may include a
glycerol, or more generally any gelatin, glycerol, and various solutions
or other formulations or preparations of same, or any other substance or
combination of substances with similar properties. In other embodiments,
the carrier may be curable. The carrier may include a polymer, blend of
polymers, or any other curable substances that can be conformed to a
target surface and then cured using, e.g., chemical curing, heat curing,
light curing, time curing, and so forth. The carrier may also be
biocompatible so that it can be safely used for in vivo imaging of
subject matter such as human dentition or a human ear canal.

[0085] In another aspect, the medium may include a carrier formed of a
transparent fluid medium and a dye that is uniformly distributed within
the carrier. The dye may consist of a single fluorescent dye having an
absorption spectrum over which the dye absorbs light and an emission
spectrum at which the dye fluoresces, wherein the absorption spectrum and
the emission spectrum have at least one overlapping non-zero region. This
single-dye formulation improves upon carriers used in, e.g., conventional
ERLIF by reducing to one the number of fluorescent dyes required in the
medium. By adapting the imaging hardware and developing a suitable
mathematical approach, the applicants have devised a technique for
capturing images with a medium that contains a single fluorescent dye.
Thus it should be appreciated that in this context any reference to a
single dye, single fluorescent dye, single fluorescent substance, or the
like is intended to refer to exactly one fluorescent substance, that is,
one and only one fluorescent substance and no more than one fluorescent
substance, which marks a significant departure from and improvement upon
previous ERLIF imaging techniques.

[0086] The carrier may be one or more of an oil, a gel, a gas, and a
liquid. For example, the carrier may include a silicon oil or a glycerol.
The dye may be fluorescein sodium. The carrier may be curable, as
generally discussed above, and the carrier may be biocompatible. In one
embodiment, the dye may be encapsulated in silica nanoparticles. The
composition may have an absorption spectrum including a peak within a
visible light, which may be a local maximum or an absolute maximum. The
composition may similarly have an emission spectrum including a peak
within a visible light range.

[0087] FIG. 5 is a flow chart of a method for three-dimensional imaging
using a luminescent layer applied to a target surface of an object.

[0088] The method 500 may begin with applying a luminescent layer to a
target surface as shown in step 502. The luminescent layer, which may be
a fluorescent layer, a chemiluminescent layer, an electroluminescent
layer, and so forth, may be applied using any of the techniques described
above including spraying, painting, dip-coating and so forth, or by
fabricating the object from a fluorescent material. For example, this may
include applying a fluorescent layer to the target surface as a
fluorescent pigment in a liquid carrier. The luminescent layer may emit
light at a first wavelength and a second wavelength, such as in response
to any of the excitation sources or other stimuli described above. In
other embodiments, the luminescent layer may emit light at a first
wavelength, such as due to fluorescence, and reflect light at a second
wavelength, where the first wavelength and the second wavelength are used
to obtain thickness measurements of a surrounding medium.

[0089] As shown in step 504, the method 500 may include distributing a
medium such as any of the media described above between the luminescent
layer and a sensor. It will be appreciated that this may include a
variety of techniques for interposing a medium between the object and the
sensor, such as pouring the medium in liquid form into a container with
the object, immersing the object in the medium, or supplying a gas into a
chamber with the object. In another aspect, this may include inflating a
balloon, bladder, or other inflatable membrane with a gas that contains a
fluorescent dye, and then inserting the sensor into the inflatable
membrane. In another aspect, this may include inserting an object into a
sock or other enclosure before distributing the medium as described
above.

[0090] In some embodiments a balloon or the like containing the medium may
be pushed against, placed upon, or otherwise brought into contact with an
object so that it conforms to a target surface. The interior of a balloon
in this posture may be used to obtain a three-dimensional impression of
the target surface against the balloon using any of the techniques
described herein. Thus it will be appreciated that techniques described
herein for measurement of interior cavities may also or instead be
adapted to measurements of any surface. In one aspect, a device deploying
the inflatable membrane may be specifically adapted to this purpose, such
as by inflating a membrane within a cone (which may also form a sealed
interior along with the membrane) or at the end of a supporting handle
that facilitates placement of the inflatable membrane against an object.

[0091] As shown in step 506, the method 500 may include exciting the
luminescent layer so that it provides some combination of reflected light
and/or radiant light. As discussed above, this may include one or more
wavelengths of light from an excitation source that are reflected off the
target surface and/or one or more wavelengths of light radiating from the
luminescent layer due to fluorescence, electroluminescence,
chemiluminescence, or any other suitable mechanism so that the
luminescent layer emits light as described in step 502. The luminescent
layer may include a fluorescent layer that emits light at the first
wavelength and the second wavelength in response to an excitation light
source, so that exciting the luminescent layer as described herein
includes exciting the fluorescent layer with the excitation light source
to provide a fluorescent emission from the fluorescent layer. The
luminescent layer may be excited with an excitation source such as a
broadband light source or any other light source that provides light at
one or more wavelengths other than the first wavelength and the second
wavelength. The excitation light source may also or instead include one
or more lasers, one or more light emitting diodes, an incandescent lamp,
and so forth. In another aspect, a waveguide may be built into the object
or target surface and serve directly as the luminescent layer.

[0092] As shown in step 508, the method 500 may include measuring an
intensity of the first wavelength and an intensity of the second
wavelength in a direction of a location on the target surface with the
sensor, which may for example be any of the sensors described above.

[0093] As shown in step 510, the method 500 may include determining a
thickness of the medium in the direction of the location based upon a
function of the intensity of the first wavelength and the intensity of
the second wavelength. It will be understood that the actual relationship
between wavelength intensities and thickness may depend on a variety of
factors such as the nature of the luminescent layer, the coefficient of
attenuation of various wavelengths by the medium, an intensity of the
excitation source, and so forth. Where the sensor provides measurements
from a plurality of pixel locations (corresponding to a plurality of
locations on the target surface), a two-dimensional array of such
intensity measurements may be used to obtain a two-dimensional array of
thickness calculations.

[0094] A more detailed analytical development of calculating or
determining thickness using a fluorescent surface is now provided. The
fluorescence characteristics of a target surface and the characteristics
of the absorbing medium may be chosen so that a part of the fluorescence
spectrum is absorbed more than other parts of the fluorescence spectrum.
For example, where two intensity bands (also referred to herein simply as
intensities) centered on wavelengths λ1 and λ2 are
measured, the medium's absorptivity coefficients ε.sub.λ1
and ε.sub.λ2 should be different. Where a band centered
around λ1 is the preferentially absorbed band, then
ε.sub.λ1>ε.sub.λ2. The normalized measured
intensities of both wavelength bands traveling from the fluorescent
surface to an image sensor located a distance d within the medium (or d
through the medium for a sensor outside the medium) and away from the
surface may be described by the following equations:

[0095] The intensity of the bands at the fluorescent surface,
I.sub.λ1,x=0 and I.sub.λ2,x=0, is dependent purely on the
fluorescence properties of the surface and the spectrum and intensity of
the excitation illumination. Though variations in excitation intensity
may change the intensity of the fluorescence at the surface, any change
in the ratio of I.sub.λ1,x=0 and I.sub.λ2,x=0 will be
negligible. Therefore, one can take the ratio of the normalized
intensities from [Eq. 1] and [Eq. 2] above and obtain an expression that
is solely dependent on depth and the concentration and absorption
coefficients of the medium:

[0096] Conspicuously, the intensity ratio decreases exponentially as the
distance through the medium increases. This relationship permits a
calculation of thickness through the medium. It will be appreciated that
in practice, actual measurements may be obtained and fit to this
relationship using any suitable techniques in order to provide calibrated
thickness measurements from a working system.

[0097] As shown in step 512, the method 500 may include reconstructing a
three-dimensional image of the target surface. This may include, for
example constructing a three-dimensional image of the region of interest
with a plurality of measurements from the sensor using any of a variety
of geometric constraints along with thicknesses of the medium as
calculated from intensity measurements. The geometric constraints may for
example include any spatial information about boundaries of the medium,
such as at least one known surface of the medium that can be combined
with one or more thickness measurements (and a direction for same) to
derive a surface point on the target surface. It will be appreciated that
the at least one known surface may be any of a variety of surfaces in the
various embodiments discussed herein where spatial information about the
surface (or more specifically, the surface-medium boundary) is known.
Thus for example, a known surface may be an exposed top surface of a tank
that contains the medium in a liquid form, or an interior side surface or
bottom surface of a transparent container of the medium. The known
surface may also or instead include a camera lens or other optical
element that separates sensors from a gaseous medium. More generally, any
spatial boundary of the medium that is known or can be measured may serve
as the at least one known surface used in three-dimensional
reconstruction as described in the various methods and systems herein. In
addition, any number of three-dimensional images may be combined through
registration or the like to form a composite three-dimensional image of
some or all of the target surface.

[0098] It will be understood that numerous variations to the above method
500 are possible, including variations adapted to particular imaging
techniques. For example, where a gas is used as a medium, the method 500
may include providing a transparent barrier between the target surface
and the sensor to retain the gas against the target surface. For example,
the object may be placed in a transparent, gas-tight chamber and filled
with a fluorescent gas. By using thickness measurements taken from
outside of the chamber, along with information about the interior
dimensions of the chamber, a three-dimensional reconstruction of a target
surface on the object may be obtained as generally described above. In
another aspect, the method 500 may include immersing the target surface
in a liquid and positioning the sensor above a top surface of the liquid
for capturing light intensity measurements. In such embodiments, the
position of the top surface of the liquid may be readily determined and
used as a basis for converting thickness measurements into a
three-dimensional reconstruction.

[0099] More generally, it will be appreciated that the method 500
described above is set forth by way of example and not of limitation.
Numerous variations, additions, omissions, and other modifications will
be apparent to one of ordinary skill in the art, and all such
modifications are intended to fall within the scope of this disclosure.
In addition, the order or presentation of these steps in the description
and drawings is not intended to require this order of performing the
recited steps unless a particular order is expressly required or
otherwise clear from the context.

[0100] Thus for example, a luminescent layer may be applied to a target
before or after a medium is distributed between the target and a sensor,
depending upon the manner in which this layer is applied. As another
example, the medium may be distributed between a target and sensor, or
the target may be immersed in a tank of the medium in liquid form, which
achieves the same purpose of placing the medium against the surface for
purposes of accurate thickness measurements. As another example, this may
include inserting a camera into a container of liquid with the target, in
which case a thickness measurement may begin at the camera lens. As
another example, this may include providing other boundary information
for the medium, such as a liquid surface location, a transparent barrier
location through which the medium may be measured, and so forth. As
another example, exciting the luminescent layer may include activating a
luminescent layer on the surface through fluorescence, phosphorescence,
electroluminescence, chemiluminescence, and so forth.

[0101] FIG. 6 is a flow chart of a method for three-dimensional imaging
using a single fluorescent dye.

[0102] As shown in step 602, the method 600 may include distributing a
medium between a target surface and a sensor, the medium including a
single fluorescent substance having a fluorescence emission spectrum that
overlaps in wavelength with a non-zero absorption spectrum of the medium.
The medium may, for example, have zero absorption at the second
wavelength. The single fluorescent substance may be fluorescein sodium,
which has emission and absorption spectra as illustrated above. Using
this or a similar fluorescent substance, the first wavelength may be
about 510 nanometers and the second wavelength may be about 540
nanometers. In another embodiment, the single fluorescent substance may
include quantum dots or other scintillants that radiate in response to
incident electromagnetic radiation. In various embodiments, the medium
may include a liquid, a gas, a solid, and/or a gel, with suitable
adaptations to the associated hardware. For example, where the medium is
a gas, the method 600 may include providing a transparent barrier or
other enclosure as described above. Where the medium is a liquid, the
method 600 may include immersing the target surface in the liquid and
positioning the sensor above the liquid.

[0103] As shown in step 604, the method 600 may include exciting the
single fluorescent substance to provide a fluorescent emission, such as
by directing a broadband light source or a light emitting diode(s) toward
the fluorescent dye and/or in the direction of the target surface.

[0104] As shown in step 606, the method 600 may include measuring the
fluorescent emission with the sensor in a direction of a location on the
target surface, including measuring an intensity at a first wavelength
and an intensity at a second wavelength, wherein the medium has a
different coefficient of attenuation for the first wavelength and the
second wavelength. Where a conventional camera or other sensor device
having a two-dimensional pixel array is employed, measuring the
fluorescent emission may include measuring the intensity of the first
wavelength and the intensity of the second wavelength from a plurality of
locations on the target surface at a corresponding plurality of pixel
locations within the sensor, thereby providing a two-dimensional array of
thickness measurements.

[0105] As shown in step 608, the method 600 may include determining a
thickness of the medium in the direction of the location based upon a
function of the intensity of the first wavelength and the intensity of
the second wavelength. This may include, for example, calculating a ratio
of the intensity of the first wavelength to the intensity of the second
wavelength.

[0106] For the case where three-dimensional imaging is performed using a
medium containing a fluorescent substance whose absorption and emission
spectra overlap, thickness can be measured by taking the intensity ratio
of two fluorescent bands centered around wavelengths λ1 and
λ2, so long as the medium self-reabsorbs one of the
fluorescent bands preferentially over the other. Supposing that only the
band centered around λ1 undergoes self-reabsorption, then
ε.sub.λ1 is some finite positive value and
ε.sub.λ2≈0.

[0107] At any point a distance x from the sensor (or a distance x into the
medium), the excitation illumination intensity Ie(x) is given by:

Ie(x)=Ioe.sup.-ε.sup.λeCx [Eq. 4]

where Io=Ie(0) is the excitation intensity at the sensor
location and ε.sub.λe is the absorption coefficient of the
medium at the excitation wavelength λe.

[0108] The fluorescent emissions contributed by a differential element
within the medium in the two bands centered around wavelengths
λ1 and λ2 are given by:

dIf1=Ie(x)ε.sub.λeCΦη1dx [Eq. 5]

dIf2=Ie(x)ε.sub.λeCΦη2dx [Eq. 6]

where Φ is the medium's quantum efficiency, or ratio of the energy
emitted to the energy absorbed, and η1 and η2 are the
relative emissions of the medium at the two wavelengths λ1 and
λ2. If ε.sub.λ1>0 and
ε.sub.λ2≈0, the first wavelength band will undergo
absorption while the second band will not. Where the excitation
illumination intensity is much greater than any fluorescent emission, any
intensity increase in both the reabsorbed and the non-reabsorbed
wavelength bands can be neglected. Consequently, the differential
fluorescence intensity equations including the reabsorption of the
λ1 band can be written as:

[0111] This relationship permits a calculation of thickness through the
medium. It will be appreciated that in practice, actual measurements may
be obtained and fit to this relationship using any suitable techniques in
order to provide calibrated thickness measurements from a working system.

[0112] As shown in step 610, the method 600 may include constructing a
three-dimensional image of a region of interest with a plurality of
measurements from the sensor using any of a variety of geometric
constraints such as known boundaries of the medium or a container
therefore along with thicknesses of the medium as calculated from
intensity measurements. In addition, a number of such three-dimensional
images may be combined through registration or the like to form a
three-dimensional image of some or all of the target surface.

[0113] It will be appreciated that the method 600 described above is set
forth by way of example and not of limitation. Numerous variations,
additions, omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation of
these steps in the description and drawings is not intended to require
this order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, for
example, a fluorescent or other luminescent surface may be excited before
a medium is distributed between a target and a sensor, or a
phosphorescent substance may be readily substituted for the fluorescent
substance. All such modifications are intended to fall within the scope
of this disclosure, which should be interpreted in a non-limiting sense.

[0114]FIG. 7 is a flow chart of a method for three-dimensional imaging
based upon absorption. In this method 700, a predetermined color on the
target surface is used in combination with a broadband light source to
obtain a reflection at two different wavelengths, one of which is
attenuated more by an intervening medium than the other. A variety of
predetermined colors may be used. For example, the color may be a
specific color (e.g., blue), or the color may be unknown provided it is
uniform over the target surface. In other embodiments, a known color
distribution may be used, such as to provide different measurement
scaling or gain.

[0115] As shown in step 702, the method 700 may begin with distributing a
medium between a target surface and a sensor, the target surface having a
predetermined color over a region of interest, which may be any area
within a target surface of an object. The medium may be characterized by
a first attenuation coefficient at a first wavelength and a second
attenuation coefficient different from the first attenuation coefficient
at a second wavelength. The first attenuation coefficient may be zero, or
more generally any value less than the second attenuation coefficient.

[0116] The sensor may be any of the sensors described above suitable for
capturing an intensity at the first wavelength and the second wavelength.
In one aspect, the sensor may be a CCD array or the like that measures
the intensity of the first wavelength and the intensity of the second
wavelength from a plurality of locations within the region of interest at
a corresponding plurality of pixel locations within the sensor, thereby
providing a two-dimensional array of thickness measurements.

[0117] In one aspect, the medium may be any of the media described above,
such as a solid, a liquid, a gel, or a gas. The medium may include any
substance or combination of substances that results in different
coefficients of attenuation at the first and second wavelengths. Where
the medium is a gas, the method 700 may include providing a transparent
barrier between the target surface and the sensor to retain the gas
against the target surface. Where the medium is a liquid, the method 700
may include immersing the target surface in the liquid and positioning
the sensor above a top surface of the liquid.

[0118] As shown in step 704, the method 700 may include illuminating a
location in the region of interest, such as with a broadband light
source, a laser, one or more light emitting diodes, or more generally,
any excitation source capable of illuminating the location in a manner
that permits a capture of reflected wavelengths at the sensor. In another
aspect, illuminating the location may include illuminating with one or
more of a chemiluminescent substance, an electroluminescent substance,
and an optical waveguide in the target surface. Where the source of
illumination is disposed on the target source or within the object, it
will be appreciated that this source may itself impart the predetermined
color upon which thickness calculations are based.

[0119] As shown in step 706, the method 700 may include measuring an
intensity of the first wavelength and an intensity of the second
wavelength in a direction of the location with the sensor. The method 700
may include filtering one or more wavelengths of light between the medium
and the sensor, such as by using any of the sensor filters described
above. The method 700 may also or instead include attenuating light at
one or more other wavelengths for any of a variety of purposes such as
filtering or shaping a broadband light source, or attenuating within the
medium in order to permit additional measurements at other wavelengths
that may be used to improve overall accuracy by providing additional
thickness measurements at a pixel location.

[0120] As shown in step 708, the method 700 may include determining a
thickness of the medium in the direction of the location based upon a
function of the intensity of the first wavelength and the intensity of
the second wavelength, such as by calculating a ratio of the intensity of
the first wavelength to the intensity of the second wavelength and using
this relationship to determine thickness. A more detailed analytical
development is now provided for thickness calculations in this context.

[0121] In an absorption-based method as described herein, two intensity
bands centered on wavelengths λ1 and λ2 may be
selected where a medium's absorptivity coefficients
ε.sub.λ1 and ε.sub.λ2 are different so that
one band is preferentially absorbed over the other (or alternatively
stated, a medium may be selected with differential absorptivity at
desired wavelengths). The illumination source may contain the wavelengths
λ1 and λ2, and the properties of the surface may be
such that these two bands are easily reflected back towards the sensor.
Provided the surface has a known, uniform color, or an otherwise known
color pattern, the ratio of intensities will vary predictably with
thickness of the medium.

[0122] The geometry of the sensor and the illumination source need to be
considered when calculating three-dimensional geometry in this context
because the wavelengths are absorbed as soon as the illumination source
rays begin traveling through an absorbing medium. The simplest case
involves a coaxial imaging optical train and illumination source. Here,
the absorption distance traveled is simply equal to twice the distance of
the sensor to the surface (or the medium boundary to the target surface),
so that [Eq. 3] above becomes:

[0123] Here, R1 and R2 are the reflectivities of the surface at
wavelengths λ1 and λ2, respectively. Because the
intensity ratio decreases exponentially as the distance through a medium
increases, this relationship permits a calculation of thickness through
the medium. It will be appreciated that in practice, actual measurements
may be obtained and fit to this relationship using any suitable
techniques in order to provide calibrated thickness measurements from a
working system.

[0124] As shown in step 710, the method 700 may include reconstructing a
three-dimensional image of the target surface. This may include, for
example, constructing a three-dimensional image of the region of interest
with a two-dimensional array of thickness measurements (such as from a
two-dimensional array of sensor measurements). This may further include
constructing a three-dimensional image of the target surface from a
plurality of three-dimensional images of a plurality of regions of
interest, such as by registering or otherwise combining multiple
three-dimensional images.

[0125] It will be appreciated that the method 700 described above is set
forth by way of example and not of limitation. Numerous variations,
additions, omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation of
these steps in the description and drawings is not intended to require
this order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, for
example, a system may measure intensity through a medium at three or more
different wavelengths in order to improve accuracy. As another example,
the three-dimensional reconstruction may include locating one or more
boundary surfaces of the medium using any number of fiducials within an
imaging chamber that holds the medium. As another example, the color or
color pattern of the target surface may be predetermined by capturing a
color image of the target surface without an intervening medium that
selectively absorbs particular wavelengths. This baseline image may
provide the predetermined color pattern needed for subsequent thickness
calculations once a selectively-absorping medium is introduced between
the target surface and a sensor. The color image may, for example, be
captured from the same sensor(s) used to capture intensity data for
thickness calculations, or from a separate color camera or the like. All
such modifications are intended to fall within the scope of this
disclosure, which should be interpreted in a non-limiting sense.

[0126] FIG. 8 illustrates a computer-implemented method for
three-dimensional imaging using the technique described above. The method
800 may be implemented, for example, as a computer program product
embodied in a computer-readable medium that when executing on one or more
computing devices performs the recited steps.

[0127] As shown in step 802, the method 800 may begin by characterizing a
color over a region of interest on a target surface to provide a
predetermined color for the region of interest. In order to perform
thickness calculations as described in this embodiment, calculations
exploit a known color of the target surface (or more specifically, a
known reflectance at two or more specific wavelengths, although these two
somewhat different notions are treated as the same for the purposes of
this description). Where the target surface has a known, uniform color,
the predetermined color may be characterized in computer memory as one or
more scalar values that describe the color for the entire target surface
(e.g., with a specific wavelength or RGB components of a measured color),
or that describe a reflectance of the surface at two or more wavelengths
where measurements are taken. Where a variable pattern or the like is
used, the predetermined color may be stored as an array that
characterizes the spatial distribution of the color pattern on the target
surface.

[0128] As shown in step 804, the method 800 may further include
characterizing a first attenuation coefficient at a first wavelength and
a second attenuation coefficient at a second wavelength of a medium
distributed between the target surface and a sensor. These values are
used to evaluate the (expected) attenuation of light reflected from the
target surface toward the sensor so that thickness can be calculated. In
general, the attenuation coefficients may be assumed based upon the
medium and any substances mixed in or otherwise distributed throughout
the medium, or the attenuation coefficients may be measured using any
suitable techniques, such as in a calibration process or the like.

[0129] As shown in step 806, measurements may be received from the sensor,
which may be any of the photosensors, pixel arrays, or other sensors
described above that capture intensity in a direction of a location in
the region of interest. The measurements of an intensity at the first
wavelength and an intensity at the second wavelength may be provided as
signals to a processor (or memory associated with a processor) for use in
subsequent calculations.

[0130] As shown in step 808, the method 800 may include calculating a
thickness of the medium in the direction of the location based upon a
function of the intensity of the first wavelength and the intensity of
the second wavelength. Suitable calculations are described above.

[0131] As shown in step 810, and as described more generally above, a
three-dimensional reconstruction of the target surface may be obtained.
In this reconstruction process, thickness measurements may be converted
into a three-dimensional image of the target surface using, e.g., a
combination of thickness measurements and associated directionality along
with information about the geometry of the medium through which thickness
measurements are captured. Individual three-dimensional images may also
be aggregated into a composite three-dimensional image using any suitable
registration techniques.

[0132] It will be appreciated that the method 800 described above is set
forth by way of example and not of limitation. Numerous variations,
additions, omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation of
these steps in the description and drawings is not intended to require
this order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, for
example, characterizing a color of a target surface may include imaging
the target surface with spectroscopic hardware that provides sufficient
information on surface characteristics (without an intervening
attenuating medium) to permit attenuation-based thickness measurements.
In addition, the characterization of color, as well as attenuation
coefficients, may be performed before, during, or after the capture of
wavelength-specific intensity information. All such modifications are
intended to fall within the scope of this disclosure, which should be
interpreted in a non-limiting sense.

[0133]FIG. 9 shows a method for using a single camera to measure
thickness. It will be appreciated that the method 900 described with
reference to FIG. 9 may be embodied in a camera and processor coupled
together and operating as described, or the method 900 may be embodied in
a computer program product including computer-executable code that when
executing on one or more computing devices performs the recited steps.

[0134] As shown in step 902, the method 900 may begin with receiving a
color image from a camera. The camera may, for example be any
commercially-available color camera that provides a two-dimensional image
containing intensity measurements at, e.g., a red wavelength, a green
wavelength, and a blue wavelength. The camera may instead be a
commercially-available color camera that provides a two-dimensional image
containing intensity measurements at a cyan wavelength, a magenta
wavelength, and a yellow wavelength. It will be understood that each such
intensity measurement may, as a practical matter, represent an intensity
across a range of wavelengths detected by the corresponding sensors,
which may be relatively broad or narrow band measurements about the
respective red, green, and blue center frequencies according to the
filters, sensor sensitivity, and other hardware and processing
characteristics of the camera. The two-dimensional image may take any
number of forms, such as three arrays of pixel values for each of the
red, green, and blue images.

[0135] As shown in step 904, the method 900 may include processing the
color image to determine, for each one of a plurality of pixels of the
camera, an intensity at a first wavelength and an intensity at a second
wavelength. Where the camera provides direct measurement at the
wavelengths of interest, such as through a corresponding use of filters,
these values may be used directly in subsequent thickness calculations.
Where the camera instead provides RGB or CMY data, the wavelengths of
interest may be inferred from the discrete color values contained in the
image.

[0136] As shown in step 906, the method 900 may include calculating a
thickness of a medium in a direction from the camera corresponding to
each one of the plurality of pixels based upon the intensity at the first
wavelength and the intensity at the second wavelength, along with a known
coefficient of attenuation of the medium for each of the first wavelength
and the second wavelength. More generally, any of the techniques
described above may be employed with a conventional color camera and
suitable corresponding processing to capture thickness measurements as
described herein.

[0137] As shown in step 908, the method 900 may include providing a
three-dimensional reconstruction of a target surface, such as using any
of the techniques described above. Step 908 may be performed by the same
processor that provides thickness calculations, or the thickness data may
be transferred to another process, processor, or machine that takes
thickness data along with other geometric information (such as boundary
information for a medium) and reconstructs a three-dimensional image of a
target surface. In one embodiment, thickness calculations may be usefully
integrated into a single device that contains the camera and the
processor, and that provides as an output an array of thickness
calculations for use, e.g., in a desktop computer that performs
subsequent three-dimensional reconstruction.

[0138] It will be appreciated that the method 900 described above is set
forth by way of example and not of limitation. Numerous variations,
additions, omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation of
these steps in the description and drawings is not intended to require
this order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. All such
modifications are intended to fall within the scope of this disclosure,
which should be interpreted in a non-limiting sense.

[0139] In another aspect, a system described herein may include an imaging
means such as a camera or any similar sensor or collection of sensors as
described above for capturing a color image, along with a processing
means including any of the processors or the like described herein that
has been programmed to perform the data processing steps above.

[0140] FIG. 10 illustrates an adaptation of the techniques described
herein to imaging of an interior space such as a human ear canal. As
shown in FIG. 10, a system 1000 may include an inflatable membrane 1002
formed about an interior space 1004 with an interior surface 1006 and an
exterior surface 1008, a seal 1010 having a first port 1012 and a second
port 1014, a supply 1016 of a medium 1018, a pump 1020, a light source
1022, a sensor 1024, and a computer 1025 with a processor 1026 and other
hardware 1028. It will be understood that, while the system 1000 may be
used with any of the inventive imaging techniques described herein, the
system 1000 may also or instead be adapted for use in known film
thickness measurement techniques such as ERLIF or any other similar
technology.

[0141] In general operation, the supply 1016 delivers the medium 1018 into
the interior space 1004 of the inflatable membrane 1002 under pressure so
that the inflatable membrane 1002 expands to fill an interior measurement
volume (not shown). When the inflatable membrane 1002 is inflated so that
it is in contact with and takes the shape of some portion of the interior
measurement volume, the light source 1022 may illuminate the interior
surface 1006 of the inflatable membrane 1002, and the sensor 1024 may
capture intensity measurements at two or more wavelengths using any of
the techniques generally described above. The resulting measurements may
be received by the processor 1026 which may determine a thickness of the
medium 1018 within the interior space 1004 at one or more locations on
the interior surface 1006 of the inflatable membrane 1002, and these
thickness measurements may be further processed to obtain a
three-dimensional image of a portion of the interior surface 1006.

[0142] The inflatable membrane 1002 may be a balloon or the like formed
about an interior space 1004. In general, the inflatable membrane 1002
may be an elastic membrane formed of any rubber, elastic, or other
material that can be stretch to expand when filled with a pressurized gas
or other material. In embodiments, the inflatable membrane 1002 may also,
or instead, be any expandable membrane, elastic or inelastic, that can be
pressurized or filled with material to increase an interior (and/or
exterior) volume. Thus for example the inflatable membrane 1002 may be
any of the membranes described above, or an inelastic membrane such as an
expandable membrane formed from a number of non-porous, inelastic panels
such as MYLAR films or the like. This approach permits the inflated shape
of the inflatable membrane 1002 to be matched to an anticipated cavity
shape or size. In another aspect, the inflatable membrane 1002 may have a
substantially spherical or ovoid shape and be fabricated of a material
that permits the inflatable membrane 1002 to stretch and expand to fill a
cavity. It will be readily appreciated that different sized balloons and
other inflatable membranes may be employed in different cavities.

[0143] The inflatable membrane 1002 may be non-porous or otherwise capable
of retaining a pressurized gas or other material in an interior thereof
so that it can be inflated within an interior volume and, under pressure,
take the form of the interior volume. In one aspect, the inflatable
membrane 1002 may be sufficiently flexible and elastic to closely follow
any contours of the interior volume as it inflates therein, and
sufficiently thin that a measurement of the interior surface 1006 can be
used to accurately infer a shape of the exterior surface 1008 when the
inflatable membrane 1002 is inflated to contact the wall of such an
interior volume. More generally, any membrane capable of retaining a
material within its interior space and capable of expanding to fill an
interior volume in a manner that closely follows the surface contours
thereof may be employed as the inflatable membrane 1002.

[0144] It will be appreciated that many variations are possible, and that
any surface of the inflatable membrane 1002 may be used for imaging. For
example, the inflatable membrane 1002 may be fabricated from a
transparent material, and the exterior surface 1008 may be coated with a
fluorescent or luminescent layer. In such embodiments, a
three-dimensional reconstruction may account for the thickness of the
inflatable membrane 1002 when reconstructing a target surface. In another
aspect, a surface such as the interior surface 1006 may have a
predetermined color such as a known, uniform color or a predetermined
color distribution to permit the use of certain imaging techniques
described above. In another embodiment, the cavity that is to be imaged
may itself have a known color, or have a fluorescent or luminescent
coating applied thereto. Such a cavity may be imaged with an inflatable
membrane 1002 that is transparent and contains one of the imaging media
described above, with suitable adjustments to account for the thickness
of the inflatable membrane 1002 between the medium and the surface of the
cavity.

[0145] A seal 1010 may be used to isolate the interior space 1004 from an
ambient environment such as air at atmospheric pressure. The seal 1010
may include any number of ports such as a first port 1012 and a second
port 1014 for accessing the interior space 1004. In embodiments, the seal
1010 may include an o-ring or the like, allowing for omission of the
sleeve 1015. In such embodiments, a tight fit between the o-ring and the
optics, electronics and so forth that are inserted through it can retain
the pressurized gas (or liquid medium, or the like) within the interior
space 1004.

[0146] The first port 1012 may, for example, be a fluid port having an
open end within the interior space 1004 and may serve as a supply port to
deliver a medium such as a gas or any of the other media described above
into the interior space 1004 under pressure so that the inflatable
membrane 1002 can be inflated with a medium that is used to facilitate
thickness measurements. The first port 1012 may include a valve 1013 or
the like to control delivery of the medium 1018 into the interior space
1004.

[0147] The second port 1014 may serve as an access port for optics, light
sources, and the like that might be inserted into the interior space 1004
to capture data for thickness measurements. The second port 1014 may be
coupled to a sleeve 1015 that physically contains such hardware as it is
inserted into and removed from the interior space 1004. In one aspect,
the sleeve 1015 may be an elastic or extendable sleeve that is coupled to
the light source 1022 and/or sensor 1024 and permits the light source
1022 and/or sensor 1024 to move about within the interior space 1004 of
the inflatable membrane 1002 when inflated. In another aspect, the sleeve
1015 may be a transparent, rigid shell or the like defining an access
space 1017 within the inflatable membrane 1002 and physically isolated
from the remainder of the interior space 1004 that is pressurized and
medium-filled. In this manner an optical supply such as a fiber optic
bundle or the like, lenses, filters, or other optics, sensors, light
sources, electronics (e.g., for operation of the sensors and/or light
sources), wires or other electrical coupling for a power supply, and so
forth can be freely inserted into and removed from the interior space
1004 (or more precisely, the access space 1017 within the interior space
1004) while preserving the seal 1010 on the inflatable membrane 1002 and
retaining, e.g., a pressurized gas or the like. In another aspect, the
sleeve 1015 (or a window, viewport, or the like within the sleeve 1015)
may be index-matched to the medium so that it has substantially the same
index of refraction as the medium. This may provide a substantially
undistorted optical path into the medium-filled interior space 1004.

[0148] The supply 1016 may be any reservoir, tank, or other container that
holds a supply of a medium 1018, which may be any of the media described
above such as a gas, liquid, gel, or the like. In general, the supply
1016 may be any supply capable of pressurized delivery of the medium
1018. In embodiments, the supply 1016 may include a pump 1020 or other
device to deliver the medium 1018 through the first port 1012 and into
the interior space 1004 under pressure, or similarly to withdraw the
medium 1018 from the interior space 1004. The pump 1020 may be any
electro-mechanical device capable of pressurized delivery of the medium
1018 including a rotary-type pump, a peristaltic pump, a
reciprocating-type pump, a centrifugal pump, an eductor-jet pump, a
hydraulic ram pump, and so forth. The supply 1016 may include a user
control, which may be remotely activated by the computer 1025 or provided
as a switch, knob, dial, or the like on the supply 1016 that electrically
controls the pump 1020. In embodiments, the supply 1016 may include a
plunger, lever, knob or similar device for manual application of pressure
to the medium 1018, or for other mechanical delivery (also under
pressure) of the medium 1018, any of which may serve as the pump 1020 as
that term is used herein. More generally, the supply 1016 may be coupled
to the interior space 1004 in any manner that permits selective delivery
of the medium 1018 into the interior space 1004. The pump 1020 may, for
example, deliver the medium 1018 with a controlled pressure, or may
deliver a controlled volume of the medium 1018, or may operate according
to any other suitable criteria. In another aspect, the supply 1016 may be
a pressurized elastic container that contracts to deliver the medium
1018.

[0149] The light source 1022 may include any of the light sources
described above. In one aspect where the inflatable membrane 1002 is
rendered luminescent, the light source 1022 in the access space 1017 may
be omitted. In one aspect, the light source 1022 may be shaped and sized
for insertion into the access space 1017 (through the second port 1014)
or otherwise positioned within the interior space 1004. In another
aspect, the light source 1022 may be, e.g., a luminescent layer
distributed on the interior surface 1006 or directly on a target surface
of an interior cavity, or the light source 1022 may be positioned on the
seal 1010 or in any other location to achieve illumination of a location
on a target surface of the inflatable membrane 1002 suitable for the
measurement techniques described herein.

[0150] The sensor 1024 may include any of the sensors described above. The
sensor 1024 may be shaped and sized for insertion into the access space
1017 through the second port 1014, or otherwise inserted into the
interior space 1004 of the inflatable membrane 1002. In one aspect, a
fiberscope or boroscope may be used (either within the access space 1017
or with the sleeve 1015 attached thereto), optionally with any suitable
lens such as a prism or mirrored surface with a conical, parabolic,
angled, or other tip (which may also be index-matched to the medium
1018). It will be understood that in such embodiments, the sensor 1024
may have a field of view that captures measurements from a cylindrical
cross-section of the interior space. This may present a significantly
different geometry and different directionality for intensity
measurements as compared to a conventional camera and lens, and suitable
adjustments to groups of spatial measurements and any subsequent
three-dimensional reconstruction may be appropriate.

[0151] In some embodiments, a transparent index-matched tip of known
dimensions can be added to a fiberscope in order to improve the optical
path through the medium 1018. This may allow the use of
higher-absorptivity media, thus increasing the depth resolution of the
system at larger distances from the tip. In other words, such a tip can
shift the exponential curve that relates ratio to depth so that the
relationship permits greater depth measurements.

[0152] The computer 1025 may include a processor 1026 such as any of the
processors or other computing devices described above. The computer 1025
may also include other hardware 1028 such as input/output interfaces,
memory, and so forth. The other hardware 1028 may in general include any
hardware that operatively couples to the sensor 1024, the light source
1022, and the supply 1016. In one aspect, the other hardware 1028 may
include an electronic imaging device such as optical transducers or a
pixel array with inputs coupled by fiber optics to the sensor 1024. In
another aspect, the other hardware 1028 may include an illumination
source coupled by fiber optics to the light source 1022. In another
aspect, the sensor 1024 and/or light source 1022 may be electronic
devices electronically coupled to the computer 1025 with wires or the
like. In another aspect, the light source 1022 and sensor 1024 may be
self-powered and wirelessly coupled to the computer 1025 for control and
operation of same. The computer 1025 may also be coupled to the supply
1016, and may control operation of the pump 1020 to deliver the medium
1018 to (and/or remove the medium 1018 from) the interior space 1004 of
the inflatable membrane 1002.

[0153] The inflatable membrane 1002 may include a cap 1030, which may be a
soft, pliable cap formed of a soft foam or similar substance. The cap
1030 may protect an insertion site such as a human ear canal during
insertion of the inflatable membrane 1002, such as where the sleeve 1015
is formed of a hard material that might otherwise cause discomfort or
physical damage.

[0154] It will be understood that the system 1000 may also include any of
a variety of other status sensors, spatial sensors, and so forth which
may cooperate with the computer 1025 to control operation of the system
1000 and monitor status thereof.

[0155] In general, the system 1000 may be adapted to use with any of the
imaging techniques described above. For example, where the imaging
technique uses a fluorescent layer applied to a target surface, the
inflatable membrane 1002 may be adapted so that the interior surface
1006, the exterior surface 1008, or the inflatable membrane 1002 includes
a fluorescent material (such as and without limitation coumarin-153) or
the like. Thus in one aspect there is disclosed herein an inflatable
membrane that includes a fluorescent interior surface, which membrane may
be employed to capture three-dimensional images of an interior volume in
which the membrane is inflated. Similarly, a predetermined or known color
may be employed on the interior surface as generally described above
(although additional refinements to the processing might be required
where, for example, the color of the balloon changes as it expands), or
the predetermined color may be on or applied to a target surface in a
cavity.

[0156] The system 1000 for interior measurement may be more specifically
adapted to a particular imaging context. For example, the inflatable
membrane 1002 may be shaped and sized for insertion into (and inflation
within) a human ear canal, or more specifically, may have a compressed
(e.g., non-inflated) shape that is shaped and sized for insertion into a
human ear so that the inflatable membrane 1002 may be inserted into the
ear canal, inflated, and then used to capture a three-dimensional image
of the ear canal. More generally, the system 1000 may be usefully
employed to image biological cavities such as a bladder, stomach, ear
canal, and so forth, or to image machine parts such as piston chambers,
tanks, and other containers.

[0157] In one aspect there is disclosed herein a system including an
inflating means, an illuminating means, a sensor means, and a processor
means. The inflating means may be the supply 1016 or any other means for
inflating the inflatable membrane with a medium that absorbs a first
wavelength of light more than a second wavelength of light. The
illuminating means may include the light source 1022 described above or
any other means described herein for illuminating or otherwise exciting a
surface of the inflatable membrane. The sensor means may include the
sensor 1024 or any other means described herein for measuring an
intensity of the first wavelength and an intensity of the second
wavelength at a location on the surface when illuminated by the
illuminating means. The processor means may include the processor or any
other means described herein that is programmed to calculate a thickness
of the medium in a direction of the location based upon a function of the
intensity of the first wavelength and the intensity of the second
wavelength.

[0158] In embodiments, the system 1000 may be adapted for the measurement
of more general targets, not just for interior measurements or ear
canals. In such embodiments, the inflatable membrane 1002 may be moved
into contact with a remote object so as to conform to a surface of that
object. Here, the inflatable membrane 1002 may contain or be inflated to
contain the medium. For example, the inflatable membrane 1002 may include
a floppy or otherwise highly-deformable bag containing the medium. Such
an inflatable membrane 1002 may conform to an object so that a
three-dimensional image can be obtained. This may for example be usefully
employed for quality control or parts inspection, such as with turbine
blades or other dimensional-sensitive parts. This approach permits
three-dimensional measurements without modifications of the target
object, and without exposing the target object to the medium. A variety
of other uses will be readily appreciated, and are intended to fall
within the scope of the present disclosure.

[0159] In some embodiments, the system 1000 may be adapted so that the
inflatable membrane 1002 includes more than one chamber. Each of these
chambers may be operatively coupled to its own supply 1016, each of which
contains a medium having properties that are adapted based upon the
expected dimensions of the part of a canal into which the inflatable
membrane 1002 will ultimately be disposed. For example and without
limitation, one may expect an external portion of an ear canal to be
wider than an internal portion of the same ear canal. Therefore, in
applications involving an ear canal, a first chamber corresponding to an
external part of the ear canal might be filled with less absorptive
optical media than a second chamber corresponding to an internal part of
the ear canal. Such an adaptation allows the same source illumination to
travel greater distances through the first chamber (where the distances
are expected to be longer) than through the second chamber (where the
distances are expected to be shorter). In embodiments, optical
characteristics of the media may be tuned with dye composition and/or dye
concentration, as well as with different fluorescent coatings for each
chamber. The sleeve 1015 may pass into or through each of the chambers
and preferably is index-matched to each of the media, or a separate
sleeve may be provided for each chamber.

[0160] FIG. 11 is a flow chart of a method for obtaining a
three-dimensional image of an interior space. In general, the method 1100
may include positioning an inflatable membrane such as any of the
inflatable membranes described above within a cavity and inflating the
membrane with a medium such as any of the media described above. With
suitable illumination sources and image capture hardware, thickness
measurements may then be taken for use in a three-dimensional
reconstruction of interior walls of the cavity. The method 1100 may be
implemented, for example, using the system described above.

[0161] As shown in step 1102, the method may begin with positioning an
inflatable membrane in a cavity. It will be appreciated that this step
may be adapted to an array of interior cavities. For example, where a
biological cavity such as a stomach or bladder is being imaged, the
membrane may be compressed into a shape and size that can be inserted
through a natural opening (such as the throat) or through the bore of a
surgical tool such as an endoscope or the like. Thus, the cavity may be a
human ear canal, a stomach, a bladder, or any other biological cavity, or
more generally, any of the cavities described above. It will be readily
appreciated that the inflated and compressed sizes of the bladder and the
desired resolution of a particular image may be considered in selecting a
suitable material for the membrane, which may range from elastic
materials to very thin, flexible, inelastic films such as foils and
various composites. For use in imaging a human ear canal, for example,
the diameter of the insertion site is relatively large compared to the
cavity being imaged, and a variety of elastic materials may be suitably
employed.

[0162] It will also be understood that in various techniques that use a
membrane, the material selected for the membrane may depend in part upon
the types of surfaces expected and the surface accuracy desired for
imaging. This in some applications, detail may be important and very
thin, very elastic materials may be preferably employed in order to
improve surface detail. In other applications, high inflation pressure
may be desired and suitably strong materials may be preferred regardless
of the fidelity with which detailed surface contours are captured. In
general, a wide variety of suitable membranes are known and may be
adapted to different imaging applications. All such variations are
intended to fall within the scope of this disclosure.

[0163] As shown in step 1104, the method 1100 may include inflating the
inflatable membrane with a medium that absorbs a first wavelength of
light more than a second wavelength of light. This may be, for example,
any of the media described above. Inflation may be, for example with a
pump or other manual or automated delivery mechanism as generally
discussed above. As the inflatable membrane inflates, it may take the
form of the cavity in which it is expanding, and the medium within the
membrane may facilitate thickness measurements that can be used to
reconstruct a three-dimensional image of the interior of the cavity.

[0164] As shown in step 1106, the method 1100 may include illuminating a
surface of the inflatable membrane. This may include, for example,
activating a light source such as any of the light sources described
above, or chemically or electrically activating a luminescent substance
within the inflatable membrane (or disposed on a surface thereof). It
will be appreciated that in various embodiments described above, the
illumination may be directed at another surface, such as the wall of a
cavity that is being imaged (e.g., with a transparent membrane and a
fluorescent cavity wall). In such embodiments, the surface of the
inflatable membrane would also be illuminated regardless of the position
of the illumination source, and all such variations are intended to fall
within the scope of "illuminating" as that step is described here.

[0165] As shown in step 1108, the method 1100 may include measuring an
intensity of the first wavelength and an intensity of the second
wavelength in a direction of a location on the surface when the surface
is illuminated. This may include measuring wavelength intensities using
any of the sensors described above including, for example, using a
conical-tipped fiberscope or the like to transmit optical signals over
optical fibers to an electronic imaging device outside the membrane. In
one aspect, this may include capturing measurements in a cylindrical
field of view of a fiberscope.

[0166] As shown in step 1110, the method 1100 may include calculating a
thickness of the medium in the direction of the location based upon a
function of the intensity of the first wavelength and the intensity of
the second wavelength using, e.g., any of the techniques described above
according to the nature of the surface, the medium, and the like. Step
1110 may be performed by any suitable processor or other computing device
or combination of computing devices.

[0167] As shown in step 1112, the method 1100 may include reconstructing a
three-dimensional image of the surface based upon the thickness
measurements and available boundary information for the medium. So for
example where a clear plastic tube or other transparent, rigid sleeve is
used for sensors and the like, the thickness measurements may be
projected from the physical interface of the sleeve with the medium. Step
1112 may be performed by any suitable processor or other computing device
or combination of devices.

[0168] In some embodiments, the method 1100 includes an iteration in which
the inflatable membrane inflates to a first pressure and a calculation
determines a first thickness of the medium, as described above. Then the
inflatable membrane inflates again, this time to a second pressure, and a
calculation determines a second thickness of the medium, again as
described above. When the first measurement and the second measurement
correspond to the same point of interest on an object, and when a
plurality of such measurements are made for a plurality of points of
interest on the object, the method 1100 can include a step of generating
a compliance map that shows relative firmnesses of the object at the
points of interest, or the manner in which a cavity yields to pressure.
For example, a point of interest that shows greater change in thickness
(e.g., yields to greater pressure) between the first measurement and the
second measurement has more "give" than a point of interest that shows
less change in thickness between the measurements. Thus, step 1112 can
include or consist of calculating the compliance map and the logical flow
of the method 1100 can include a loop from step 1110 back to step 1104
for any number of measurements under different pressurization.

[0169] FIG. 12 shows a self-inflating bladder for use in interior
measurements. In general, the self-inflating bladder 1200 may include a
membrane 1202 such as a collapsible membrane including many elements of
the system 1000 described above, with differences as noted below.

[0170] The membrane 1202 may be formed around an interior space 1004, and
constructed of a material that returns to an original shape in an absence
of external forces. For example, the membrane 1202 may be formed of a
shape-memory alloy, a visco-elastic solid or foam, a photo-induced
shape-memory polymer, a shape-memory rubber, or any other film, frame,
lattice, composite exterior and/or interior structure or combination of
structures that return to an original shape. The membrane 1202 may be
shaped and sized (in its expanded form) to be larger than a cavity that
is to be imaged in one or more dimensions so that the membrane 1202, when
compressed into a compressed membrane, can be inserted into the cavity
and then expand to contact the interior wall of the cavity. More
generally in operation, the membrane 1202 may be compressed with an
application of force, and then released to expand to its original shape,
such as to fill a cavity for imaging. In one aspect, the membrane 1202
may be fabricated of a material that returns to an original shape under
user-controlled conditions such as an application of heat, moisture, an
electrical field and so forth. It will be understood that in such
embodiments, the membrane 1202 will tend to return to an original shape
in the absence of physical external forces along with an application of
the appropriate form of activation. All such variations are intended to
fall within the scope of a membrane returning to an original shape in the
absence of external forces as that phrase is used herein.

[0171] It should also be understood that the compressed membrane need not
have a reduced volume in order to be "compressed" as that term is used
herein. For example, where a generally elastic membrane is filled with a
viscous substance, the membrane may be elongated with an application of
force so that it has greater length and less thickness. In this
compressed state, the membrane may be inserted into a narrow passage
(such as an ear canal) and the membrane may then expand to abut the walls
of the passage as it returns to its original, thicker shape. Thus while a
variety of embodiments discussed herein involve displacement of a medium
into and out of a membrane, in other embodiments a collapsible membrane
may be compressed by displacing the medium within the membrane without
any overall change in volume of the membrane. In such embodiments, the
membrane may be advantageously fabricated in a sealed form without any
fluid port or the like for manipulating the medium within the membrane.

[0172] The interior space 1004 may be coupled to a supply 1016 of a medium
1018 (which may be any of the supplies and media described above) through
the first port 1012, which in this case may be a fluid port, that couples
the supply 1016 to the interior space 1004 and includes a flow restrictor
1213 or the like that controls a rate at which the medium 1018 passes
between the supply 1016 and the interior space 1004. This may include,
for example, a porous membrane, nozzle, narrowed fluid passage,
adjustable valve (for variable control of flow rate) or any other
substance or structure (or combination of these) to slow the passage of
the medium 1018 into the interior space 1004 when the membrane 1202 is
expanding. In general, by restricting a flow of the medium 1018, the flow
restrictor 1213 limits that rate at which the membrane 1202 expands in
the absence of external forces. This usefully permits the membrane 1202
to be compressed with an application of force and then released, at which
point the membrane 1202 will expand slowly enough that it can be inserted
into a cavity before it fully expands.

[0173] A sleeve 1015, which may be a shell such as any of the rigid shells
described above, may be positioned within the interior space 1004 to
define an access space 1017 for insertion of a light source 1022, sensor
1024 and the like to facilitate light intensity measurements. The sleeve
1015 may be fabricated of a transparent material, or otherwise include at
least one transparent region for such measurements. The sleeve 1015 may
extend from a seal 1010 to the cap 1030, which may be a soft, pliable cap
such as any of the caps described above. In one aspect, the sleeve 1015
may physically connect to the cap 1030 and the seal 1010, either directly
or through additional structures, to form a solid or generally rigid
structure that, along with the supply 1016 and the first port 1012, can
be used as an insertable imaging device. Where the self-inflating bladder
1200 is shaped and sized for use in, e.g., a human ear canal, the cap
1030 may be soft and/or pliable to protect the ear canal during insertion
of the device.

[0174] The cap 1030 may include a transparent window. During insertion of
the self-inflating bladder 1200 (or any other device described herein for
interior imaging) into, e.g., an ear canal or other opening, a fiberscope
can be inserted into the access space 1017 so that it has an optical view
through the window and the sensor 1024 can capture an image down the
length of the ear canal. With this view, a user may guide the
self-inflating bladder 1200 (or other device) into the canal, also
allowing the user to stop insertion before hitting, e.g., an eardrum or
other obstruction or sensitive area. The self-inflating bladder 1220 (or
other device) may include a supplemental illumination device to
illuminate the canal during insertion, or the light source 1022 may be
adapted to this purpose.

[0175] In one aspect a retainer 1216 may be provided that mechanically
retains the collapsible membrane in a compressed shape. Thus in use, the
membrane 1202 may be compressed to a size smaller than an interior
diameter of the retainer 1216, which may be for example a cylindrical
sleeve or the like, and the retainer 1216 may be fitted over the
compressed shape to retain the membrane 1202. When a three-dimensional
image is to be captured, the retainer 1216 may be removed and the
self-inflating bladder 1200 may be inserted into a target cavity and
permitted to slowly expand into the shape of the target cavity, with the
rate of expansion determined by, e.g., the viscosity of the medium 1018,
the flow restrictor 1213 positioned in the flow path, and the mechanical
force applied by the membrane 1202 as it expands toward its fully
expanded shape. It will be understood that the retainer 1216 may usefully
be formed of a rigid material (or combination of materials) or any other
material suitable for retaining the membrane 1202 in a compressed state.
The retainer 1216 may be a single structure shaped and sized to slide
over the cap 1030 and off the membrane 1202, or the retainer 1216 may be
formed of a multi-part assembly that can be, e.g., snapped together and
apart around the membrane 1202, or that hingeably encloses the membrane
1202, or otherwise removably retains the membrane 1202 in a compressed
shape. The compressed shape may be shaped and/or sized for insertion into
a human ear or any other cavity from which three-dimensional images are
desired.

[0176] It will be understood that while FIG. 12 shows a simple,
cylindrical shape for the membrane 1202 in its compressed state, any
shape suitable for a particular imaging application may similarly be
used, and may accommodate either the shape and size of the insertion site
or the shape and size of the cavity to be imaged, or some combination of
these. For example, the inner and outer portions of a human ear canal
have substantially different interior diameters. Thus in one aspect, the
self-inflating bladder 1200, and the membrane 1202 and retainer 1216 for
same, may have a tapered shape or a two-stage shape with a relatively
large diameter on an outer section for imaging the outer ear canal and a
relatively smaller diameter on an inner section for imaging more deeply
in the inner ear canal. Any number of similar adaptations may be made for
different imaging applications, all of which will be readily appreciated
by one of ordinary skill in the art.

[0177] FIG. 13 is a flow chart of a method for using a self-inflating
bladder such as the self-inflating bladder 1200 described above to
capture three-dimensional images of an interior space, and more
particular to capture three-dimensional images of a human ear canal.

[0178] As shown in step 1302, the method 1300 may begin with providing a
collapsible membrane that returns to an original shape absent external
forces, the collapsible membrane having an interior space. This may be,
for example, any of the membranes described above. As noted above, a
membrane that returns to an original shape absent external forces is
intended to include any structure or combination of structures that tend
to return to a shape, whether when constraining physical forces are
released (e.g., a retainer as described above) or when some form of
activation (light, heat, electricity, and so forth) is applied, or some
combination of these.

[0179] As shown in step 1304, the method 1300 may include compressing the
collapsible membrane into a shape and size for fitting into a human ear
canal. This may, for example, include compressing the membrane into a
generally cylindrical shape sufficiently narrow to fit into the ear
canal. In one aspect, a margin of time may be provided so that, when a
retainer is removed and the membrane begins to expand (as described
above), the membrane does not expand beyond the expected size of the ear
canal for a period of time in order to permit handling and insertion into
the ear canal. This may be, for example, ten seconds, or any other
duration according to user preferences or handling constraints and the
like.

[0180] As shown in step 1306, the method 1300 may include retaining the
collapsible membrane in the shape and size with a retainer such as any of
the retainers described above. In one aspect, the collapsible membrane
may be a disposable membrane with a disposable retainer. In another
aspect, the collapsible membrane may be a reusable membrane, and the
retainer may be removable and replaceable to permit multiple
redeployments of the collapsible membrane.

[0181] As shown in step 1308, the method 1300 may include coupling the
interior space to a supply of a medium in a fluid form that absorbs a
first wavelength of light more than a second wavelength of light, wherein
the interior space is coupled to the medium through a port that restricts
a flow of the medium into the interior space, such as the fluid port and
flow restrictor described above. It will be understood that in various
embodiments this coupling may occur before or after the collapsible
membrane is compressed and before or after the retainer is fitted to the
compressed membrane.

[0182] As shown in step 1310, the method 1300 may include removing the
retainer from the collapsible membrane and inserting the collapsible
membrane into a human ear canal. At this point, the membrane may begin to
expand and draw the medium into the interior space. As noted above, the
rate at which this expansion occurs may depend on any of a number of
factors such as the viscosity of the medium, the amount of flow
restriction, the pressure created by the expanding membrane, and the
pressurization (if any) of the supply. These factors may generally be
controlled during design of the collapsible membrane, and the design may
also permit manual adjustment at the time of deployment such as by
providing an adjustable valve for flow restriction.

[0183] As shown in step 1312, the method 1300 may include measurement and
three-dimensional reconstruction using any of the techniques described
above.

[0184] It will be appreciated that the method 1300 described above is set
forth by way of example and not of limitation. Numerous variations,
additions, omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation of
these steps in the description and drawings is not intended to require
this order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, for example
a medium may be coupled to the membrane before or after compression of
the membrane. Where the medium is coupled before compression of the
membrane, the supply may be used to compress the membrane using reverse
pressure (e.g., suction) to extract material from the interior space.
Similarly, while an ear canal is specifically mentioned, the approach may
be adapted to any number of biological or other cavities. All such
modifications are intended to fall within the scope of this disclosure,
which should be interpreted in a non-limiting sense.

[0185] FIG. 14 illustrates an adaptation of the techniques described
herein to capture a three-dimensional image of an object such as human
dentition. In an embodiment, a device 1400 for use in imaging dentition
may include an imaging tray 1402 with an interior surface 1404 formed
from a bottom 1406 and one or more sidewalls 1408, and any number of
fiducials 1410, along with a medium 1412 such as any of the media
described above. Although not depicted, it will be understood that the
device 1400 may be used with any suitable combination of the sensors,
light sources, processors, and so forth described above. It will further
be understood that, while the device 1400 may be used with any of the
inventive imaging techniques described herein, the device 1400 may also
or instead be adapted for use in known film thickness measurement
techniques such as ERLIF or any other similar technology.

[0186] The imaging tray 1402 may be any container suitable for receiving
an impression of an object. For dental applications, the imaging tray
1402 may be shaped and sized for use as a dental bite tray. A variety of
such containers are known in the dental art including numerous disposable
and/or reusable bite trays, impression trays, fluoride trays and the
like, any of which may be adapted for use with the techniques described
herein. In addition, while a full-arch dental tray is shown, it will be
understood that the tray may instead cover any sub-portion of an arch
such as a quadrant or a row of teeth. In other embodiments, the bite tray
may capture an upper and lower arch concurrently, which may
advantageously capture bite registration information relating to the
alignment of an upper and lower arch. It will be appreciated that while a
dental bite tray is depicted, the imaging tray 1402 may more generally
have any shape and size suitable for an object that is to be imaged. In
addition, the imaging tray 1402 may be adapted to any of the various
imaging techniques described above. This may include, for example,
fabricating the imaging tray 1402 from a transparent material so that
thickness measurements can be taken through the imaging tray 1402, or
fabricating the imaging tray 1402 from a fluorescent or other luminescent
material so that the imaging tray 1402 can serve as a light source as
described above. This may include fabricating the imaging tray 1402 from
a material with a known color or a known color distribution that can be
used in attenuation measurements as described above. This may also, or
instead, include applying a layer to the interior surface 1404, such as a
fluorescent, luminescent, or known color layer.

[0187] The interior surface 1404 may have known dimensions that can be
used in combination with thickness measurements to geometrically
reconstruct a three-dimensional image of an object impressed into the
medium 1412. In one embodiment, the known dimensions may accommodate a
dental impression in the medium 1412. More generally, geometric or
spatial information about the interior surface 1404 provides boundary
information for the medium 1412 within the imaging tray 1402 so that
thickness measurements of the medium 1412 can be converted into spatial
measurements of an impression in a common coordinate system, thus
permitting a three-dimensional reconstruction. It will thus be
appreciated that, while the imaging tray 1402 is depicted as having an
interior surface 1404 formed of two sidewalls 1408 and a bottom 1406, the
interior surface 1404 may more generally include any rectilinear,
curvilinear or other surface(s) suitable for a particular object being
imaged, provided that the shape of the interior surface 1404 is known in
areas where boundary positions are needed for a three-dimensional
reconstruction.

[0188] The bottom 1406 and sidewalls 1408 retain the medium 1412 within
the imaging tray 1402 and provide known physical boundaries for one or
more surfaces of the medium 1412 so that thickness measurements can be
converted into a three-dimensional image. It will be appreciated that the
sidewalls 1408 may be open as depicted, provided the medium 1412 is
sufficiently viscous that it will remain wholly or partially within the
imaging tray 1402 during handling and/or impressioning. Where for example
the medium 1412 is a non-viscous liquid, the sidewalls 1408 may usefully
be joined together to form a complete perimeter sidewall that retains the
liquid within the imaging tray 1402. In another aspect, one or more of
the bottom 1406 and sidewalls 1408 may be transparent, depending for
example on the direction from which thickness measurements are expected
to be taken.

[0189] Any number of fiducials 1410 may optionally be included on or
within the imaging tray 1402. The fiducials may be at known locations
and/or have a known shape. Each fiducial 1410 may have one or more
uniquely identifying characteristics so that it can be identified in an
image or other data obtained from measurements of the imaging tray 1402.
Fiducials may in general serve as useful landmarks in a three-dimensional
reconstruction by facilitating global registration of a number of
independent three-dimensional measurements and/or images. The fiducials
1410 may, for example, provide visual landmarks to an imaging system that
can be correlated to three-dimensional locations on the imaging tray 1402
or otherwise encode spatial information. More generally, the types and
uses of fiducials in three-dimensional registration will be readily
appreciated by those of ordinary skill in the art, and all such fiducials
that might be adapted to use with the three-dimensional imaging
techniques described herein are intended to fall within the scope of this
disclosure. Similarly, random or regular patterns or other surface
treatments can be employed to assist in registration, and may be adapted
for use with the imaging tray 1402 and other devices and measurement
techniques described herein.

[0190] The medium 1412 may be disposed within the interior surface 1404
and may generally include any of the media described above. In an
embodiment, the medium 1040 may be capable of yielding to form an
impression of an object inserted into the imaging tray and may, for
example, absorb a first wavelength of light more than a second wavelength
of light. The medium 1412 may include a single fluorescent dye or a
plurality of fluorescent dyes. The medium 1412 may use any number of
carriers.

[0191] For example, the medium 1412 may include a gel, liquid, or other
substance capable of accurately retaining, or being cured to accurately
retain, an impression therein. Any type of curable material (with
suitable optical properties) may be used as the carrier, including
materials that are heat-cured, pressure-cured, time-cured, light-cured,
chemically cured, or the like, as well as any combination of these. The
medium 1412 may be cured while an object is impressed therein, such as
while a patient is biting into a dental bite tray, or the medium 1412 may
be cured after the object is withdrawn. In the latter case, the medium
1412 is preferably sufficiently viscous to retain a useful impression of
the object until the medium 1412 can be cured. In other embodiments, the
medium 1412 may not be curable, but may be sufficiently viscous or
plastic to retain an accurate impression after an object is removed,
either permanently, semi-permanently, or at least long enough to obtain
light intensity measurements for thickness calculations. In other
embodiments, the medium 1412 and imaging tray 1402 may be imaged while
the object is embedded in the medium. Where the object fits entirely into
the imaging tray 1402, the imaging tray 1402 may be a simple desktop tray
filled with liquid or the like. Where the object is physically coupled to
a larger object (such as human dentition), the imaging tray 1402 may be
transparent so that measurements for thickness calculations can be
obtained through the bottom 1406 or sidewall(s) 1408.

[0192] FIG. 15 is a flow chart of a method for capturing a
three-dimensional image of an object such as human dentition using the
techniques described herein. The method 1500 may be used, for example,
with the imaging tray 1402 and medium 1412 described above.

[0193] As shown in step 1502, the method 1500 may begin with disposing a
medium within an imaging tray having an interior surface of known
dimensions, the medium capable of yielding to form an impression of an
object inserted into the imaging tray, and the medium absorbing a first
wavelength of light more than a second wavelength of light. In general,
this may include any of the imaging trays and mediums described above. In
order to dispose the medium within the imaging tray, the medium may be
poured, injected, spread, or otherwise distributed into the interior
space using any suitable tools and/or techniques for the viscosity and
other physical properties of the medium. In a prepackaged embodiment, the
medium may be disposed within the imaging tray during fabrication, and
packaged for shipment in a ready to use form. In another embodiment, the
medium may be manually disposed within the imaging tray prior to use,
such as from a tube or other container of the medium. In either case, the
imaging tray may be reusable or disposable.

[0194] As shown in step 1504, the method 1500 may include inserting an
object into the imaging tray. This may include placing an object into the
imaging tray (such as where the medium is a liquid), or applying a force
to insert the object into the medium within the imaging tray. For
example, where the imaging tray is a dental bite tray, this may include
inserting human dentition into the dental bite tray, such as by having a
user apply force by biting into the medium with the teeth and other
dentition that are the object of the impression. However inserted, the
object may in general displace the medium and form an impression of the
object within the medium.

[0195] As shown in step 1506, the method 1500 may include illuminating the
interior surface of the imaging tray. This may include any of the
illumination techniques described above.

[0196] As shown in step 1508, the method 1500 may include capturing an
image of the interior surface at the first wavelength and the second
wavelength. This may in general include any of the imaging techniques
described above. It will be understood that capturing an image in this
context is intended to refer to the direction of the surface rather than
the surface itself. Thus for example where a transparent imaging tray is
used, the image captured may be an intensity of light from a medium
behind the interior surface rather than the interior surface itself. Thus
in many embodiments the image may relate to the direction in which light
intensity is measured rather than an actual location from which light is
reflected.

[0197] Capturing an image of the interior surface may also, or instead,
include capturing a reference image of a plurality of fiducials provided
within the imaging tray. These fiducials may be used to determine a
three-dimensional position and orientation of an imaging tray using any
of a variety of known techniques. This may include processing of the same
image used to calculate thicknesses (e.g., an image of the interior
surface at the first wavelength and the second wavelength), such as by
locating and interpreting the fiducials in such images, or this may
include capturing a supplemental image with the same camera or sensor(s)
for processing of the fiducials. In another aspect, a supplemental camera
or other imaging device may be provided in order to capture a reference
image of the fiducials. In such embodiments, the supplemental camera
should have a known spatial relationship to the camera or sensors used
for thickness measurements.

[0198] As shown in step 1510, the method 1500 may include processing the
image to determine a thickness of the medium in a direction of the
interior surface. This may include any of the processing techniques
described above based upon a ratio of intensities of two different
wavelengths of light, or any other similar technique or approach. This
may include capturing a plurality of thickness measurements for a
plurality of directions toward the interior surface, such as from a
two-dimensional array of intensity measurements captured by a camera or
the like.

[0199] As shown in step 1512, the method 1500 may include obtaining a
three-dimensional reconstruction of the object from the thickness
measurement(s). This may include, for example, applying a number of
thickness measurements, in view of the known dimensions of the interior
surface, to determine a three-dimensional shape of the object, or the
boundaries of an impression of the object in the medium. It will be
understood that for a variety of reasons there may be subtle or
substantial deviations between the actual object shape and the actual
impression of the object. Either or both of these (conceptually)
mirror-imaged surfaces are intended to fall within the scope of the
three-dimensional shape of the object as that phrase is used herein.

[0200] It will be appreciated that the method 1500 described above is set
forth by way of example and not of limitation. Numerous variations,
additions, omissions, and other modifications will be apparent to one of
ordinary skill in the art. In addition, the order or presentation of
these steps in the description and drawings is not intended to require
this order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, for example
the object may be inserted into an imaging tray before the medium is
disposed therein. Or various types of fiducials may be used to relate
thickness measurements to positions within the imaging tray. Similarly,
while human dentition is specifically mentioned, the approach may be
adapted to a wide variety of biological or other subject matter, and all
such variations are intended to fall within the scope of the present
disclosure.

[0201] The systems and methods described herein can be usefully employed
to obtain high-accuracy three-dimensional images of interior spaces such
as an ear canal or other human or machine cavity by inflating a membrane
with a suitable medium or, where the cavity is sufficiently liquid-tight,
simply filling the cavity with a suitable and compatible (e.g.,
biocompatible) medium, all as described above. In general, these
techniques can be applied to obtain a complete three-dimensional model
from a single frame of wavelength data. More specifically a
three-dimensional reconstruction of a surface can be calculated by
relating particular directions through a medium (according to the image
capture geometry) to particular distances through the medium (according
to a ratio of two wavelengths in that direction), thereby providing a
three-dimensional surface of points. As a further advantage, this permits
dynamic imaging or three-dimensional video that, as the shape varies from
frame to frame, captures time-based variations in the surface. Thus in
one aspect, there is disclosed herein a technique for capturing dynamic
three-dimensional data from an interior cavity. This dynamic data has a
wide array of potential diagnostic, design, and modeling applications as
will be discussed in greater detail below.

[0202] As used herein, the term "dynamic data" is intended to refer
generally to data such as ear canal shape data that changes over time.
Two types of dynamic data are generally contemplated by this disclosure.
"Compliance" data refers to shape or surface data that is linked to
pressurization, such as for compliance of an ear canal shape to changes
in pressurization. Where an inflatable membrane has a known
pressurization, this compliance can be quantitatively measured using the
devices described above to provide compliance data that is useful for
design and customization of earpieces and other applications described
herein. On the other hand, "shape change" data refers to shape or surface
data that is linked to musculoskeletal movement of a subject. So for
example, if a subject tilts or swivels the head, opens or closes the jaw,
yawns, nods, talks, chews, or otherwise engages in movement of the head
and associated muscles, bones, or other tissue, this may yield a shape
change in the ear canal that can be measured quantitatively as shape
change data. Shape change data may be used instead of or in addition to
compliance data for the design and customization of earpieces, along with
other applications as described herein. It should be understood that the
term "musculoskeletal movement", even when limited to the head, is
intended to be broadly construed. Thus for example such movement may
include movements of cartilage, soft tissue, or any other tissue.
Similarly, other musculoskeletal movement such as shrugging the shoulders
may induce corresponding movements of head tissue and resulting changes
to the shape of the ear canal. All such movements that might result in
shape change within the ear canal are intended to fall within the scope
of "musculoskeletal movement" and/or "musculoskeletal movement of the
head" unless a different meaning is explicitly provided or otherwise
clear from the context.

[0203] FIG. 16 is a flow chart of a method for measuring compliance. The
method may be employed, for example, using any of the devices described
above to measure compliance in, e.g., a human ear canal.

[0204] As shown in step 1602, the method 1600 may begin with inserting an
inflatable membrane, such as any of the inflatable membranes described
above, into a cavity such as an ear canal.

[0205] As shown in step 1604, the method may include pressurizing the
inflatable membrane within the cavity with a fluid to a predetermined
pressure, thereby providing an inflated membrane. The predetermined
pressure may be a fixed target pressure, or the pressure may be
determined during use based upon, e.g., feedback from a patient
concerning comfort of fit. Thus in one aspect, the pressurization of the
inflatable membrane may be used to achieve a more comfortable fit for a
hearing aid or other ear device by providing information on oversizing
the ear device. Similarly, the predetermined pressure may be a pressure
that is measured after a technician or other user observes and adequate
shape, size, or fit of the inflatable membrane within a cavity.

[0206] It will further be understood that the pressure may be a
time-varying pressure or changing pressure that varies in a predetermined
manner over a predetermined interval. For example, a fixed pressure may
yield unreliable results in a typical environment where the inflatable
membrane is operated as a handheld probe and the probe may be susceptible
to independent pressure variations due to hand tremors, head tremors, and
the like. In such an imaging environment, the predetermined pressure may
be a continuously varying pressure such as a mechanically driven
pulsatile wave, sinusoidal pressure wave, triangle wave, ramp, square or
rectangle wave, and so forth. Corresponding compliance measurements may
be averaged or otherwise characterized over one or more cycles of the
pressure wave. Similarly, the frequency response of the cavity shape to
different frequencies and magnitudes of pressure variation may provide
useful information concerning the nature of the cavity walls, e.g.,
whether the underlying tissue is bone, cartilage, soft tissue, or the
like. In this context, different frequency variations may be appropriate
in different imaging environments, and may be adjusted to maximize
detected motion. Thus for example, when measuring lung compliance to
identify areas of damaged or scarred tissue, certain frequencies of
pressure variation may provide greater sensitivity to underlying tissue
variations and improve diagnostic or other value of the obtained
compliance data.

[0207] The fluid may include any liquid, gas, gel, foam, or other fluid
than can be used to inflate the membrane. Various optical properties of
this fluid are discussed above, and may be selected according to a
three-dimensional imaging technique that is being used.

[0208] As shown in step 1606, the method 1600 may include obtaining a
three-dimensional image of a surface of the inflated membrane at the
predetermined pressure. This may, for example, include capturing in image
with an image sensor or the like at two different wavelengths,
determining a thickness of the medium used to inflate the inflatable
membrane in each direction that data is captured from the image sensor,
and transforming this directional and distance data into a representation
of the surface of the inflatable membrane at a plurality of points, all
as generally contemplated above.

[0209] In one aspect, the three-dimensional image may be an image of an
outer ear canal of a patient or user with an earpiece positioned in the
ear canal. Thus the three-dimensional image of the surface may be used to
evaluate a fit of the earpiece, such as by confirming a desired position
or orientation. In such embodiments, the method 1600 may omit any further
capture of images, and stop after sufficient image data is obtained to
evaluate the fit of the earpiece.

[0210] As shown in step 1608, the method may include changing the pressure
within the inflated membrane to a second predetermined pressure different
from the predetermined pressure.

[0211] As shown in step 1610, the method may include obtaining a second
three-dimensional image of the surface of the inflated membrane at the
second predetermined pressure.

[0212] As shown in step 1612, the method may include storing a
representation of a change from the three-dimensional image to the second
three-dimensional image as compliance data for the cavity. It will be
appreciated that while a generally two-state comparison is described,
numerous variations are possible. Thus any number of static (e.g., fixed
pressure) or dynamic (e.g., varying pressure) images may be captured and
compared without departing from the scope of the invention. By imaging
with three-dimensional data captured through the medium that is used to
pressurize the inflatable membrane, any type and amount of compliance
data may be usefully captured and analyzed using the systems described
above. Thus more generally a plurality of different pressures and
pressure change frequencies and magnitudes may be used based upon the
generalized method described above.

[0213] The representation of the change in the three-dimensional image may
be stored, for example, in the memory of a computer or in a database or
any other suitable volatile or non-volatile storage medium that can store
a non-transitory representation of the corresponding data. The
representation of change may itself take a variety of forms. This may,
for example include storing the predetermined pressure and the second
predetermined pressure, or where these pressures are time-varying,
representative data such as a center frequency, magnitude, and duration
of the applied or measured pressure. The representation may also include
a number of corresponding surfaces under various pressurizations, or a
volumetric displacement resulting from the pressure changes, or some
combination of these such as an initial shape under one pressurization
scheme and displacement data for differing pressurization schemes.
Similarly, other change data may be stored such as a linear displacement
normal to the surface at one or more locations on the surface, a
deformation or other three-dimensional displacement from one image to the
next, or the like. In one aspect, the representation may be stored as a
three-dimensional video that can be retrieved and displayed for human
review. This may be particularly useful, for example, where generally
increasing or decreasing pressurization is applied to the ear canal and
an ear piece designer wishes to directly observe how the ear canal yields
to increased pressurization.

[0214] As shown in step 1614, the compliance data may be analyzed. This
may, for example, include analyzing the compliance data to quantitatively
characterize changes in response to pressurization as discussed above.
Any other analysis, such as drawing inferences concerning tissue type,
elasticity, and so forth, may also be performed.

[0215] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 16
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 1600.

[0216] FIG. 17 is a flow chart of a method for measuring shape change in a
cavity in response to musculoskeletal movements. While the following
description generally contemplates two different discrete muscoluskeletal
positions, this is the most basic formulation of measuring shape change,
and it will be appreciated that detecting continuous shape change over a
range of motion may be more useful in a variety of contexts. As such, any
number of different measurements may usefully be taken in various
applications.

[0217] As shown in step 1702, the method 1700 may begin with inserting an
inflatable membrane into an ear canal or other cavity of a subject, as
generally described above for example with reference to FIG. 16.

[0218] As shown in step 1704, the method 1700 may include pressurizing the
inflatable membrane within the ear canal with a fluid to a predetermined
pressure, thereby providing an inflated membrane, all as generally
described above for example with reference to FIG. 16. In one aspect,
this may include inflating the inflatable membrane to a target pressure
that is maintained, e.g., with a proportional-integral-derivative ("PID")
controller or the like. In another aspect, this may include inflating the
inflatable membrane to a comfortable pressure level for a subject, which
may be measured and may usefully serve as a basis for shaping and sizing
an earpiece.

[0219] As shown in step 1706, the method 1700 may include obtaining a
first three-dimensional image of a surface of the inflated membrane at
the predetermined pressure, all as generally described above for example
with reference to FIG. 16.

[0220] As shown in step 1708, the method 1700 may include causing a
musculoskeletal movement of a head of the subject, which may be broadly
understood as any of the musculoskeletal movements described above. This
may, for example, include talking, making specific vowel or consonant
sounds, yawning, opening or closing the mouth, moving the lower jaw from
side to side, moving the shoulders, tiling the head, or any other motion
or combination of motions. This may include measuring the musculoskeletal
movement of the head using any suitable manual or computerized technique,
including by way of example any of the two-dimensional or
three-dimensional image capture techniques described below. Thus in one
aspect, this may include obtaining two or more three-dimensional images
of the head of the subject to quantitatively characterize the
musculoskeletal movement.

[0221] As shown in step 1710, the method 1700 may include obtaining a
second three-dimensional image of the surface after the musculoskeletal
movement. In general, the three-dimensional images may be captured at
various times during the musculoskeletal movement. Thus in one aspect,
the two or more three-dimensional images may include at least one
three-dimensional image captured before causing the movement, at least
one three-dimensional image after causing the movement, and at least one
three-dimensional image during the movement. In this manner, ear canal
shape data for a starting position, and ending position, and any desired
number of intermediate positions may be captured for analysis.

[0222] As shown in step 1712, the method 1700 may include identifying a
change in shape of the surface between the first three-dimensional image
and the second three-dimensional image. As noted above, a number of
additional images may be obtained to help characterize a range of shape
change in the ear canal corresponding to a range of other musculoskeletal
movements. For example, extreme or minimum/maximum positions may be
misleading where the ear canal actually expands and then contracts over a
specific range of musculoskeletal movement. In addition, a full motion
video may be useful to an earpiece designer, and may be captured and
stored for later reference. In addition, two-dimensional or
three-dimensional video of the musculoskeletal movement (as distinguished
from the ear canal shape) may be captured and timewise synchronized to
the ear canal three-dimensional images in order to more fully
characterize the movements that induced the ear canal shape change. This
may be obtained using any conventional two-dimensional or
three-dimensional imaging system, the details of which are not recited
here. In such a context, a head motion video, jaw motion video, or the
like may be captured and stored with the ear canal three-dimensional
video.

[0223] As shown in step 1714, the method 1700 may include storing and
analyzing the change in shape. This may include storing the change in
shape as ear canal shape change data for the subject. Storing the change
in shape may include storing the first three-dimensional image and the
second three-dimensional image. Storing the change in shape may also or
instead include storing a movement between the first three-dimensional
image and the second three-dimensional image. Storing the shape change
data may also or instead include storing a displaced volume between the
first three-dimensional image and the second three-dimensional image. In
general, the actual change in shape may be represented in a variety of
forms that will readily be appreciated by one of skill in the art
including volumetric displacements, linear displacements, and so forth.

[0224] The analysis may include a variety of analyses based upon the shape
change and the corresponding musculoskeletal movements. This may, for
example, include relating the musculoskeletal movement to the change in
shape. This may also or instead include analyzing the ear canal shape
change data to quantitatively characterize how the ear canal changes
shape in response to the musculoskeletal movement. This may also include
characterizing the musculoskeletal movement of the head as a type of
movement and storing the type of movement. Thus, for example, the
musculoskeletal movement may be characterized as a "yawn," a "clench," or
any other suitable movement, and the data may be explicitly labeled to
reflect this movement type.

[0225] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 17
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 1700.

[0226] FIG. 18 shows an inflatable membrane within an ear canal. In
general, an inflatable membrane 1802 is positioned for use within an ear
canal 1804 and pressurized with an imaging medium 1806 as generally
described above. The inflatable membrane 1802 may contact a tympanic
membrane 1808, or a location of the tympanic membrane 1808 may be
inferred from the more general geometry of the ear canal 1804. The
inflatable membrane 1802 may be coupled to a handheld probe 1810 or other
housing, which may house imaging hardware, processing circuitry, memory,
a medium delivery and control system, and other hardware, all as
described above in greater detail. Within the inflatable membrane 1802,
sensors, a light source and other hardware may also be included, also as
described above in greater detail. Having shown the manner in which the
inflatable membrane 1802 is place for use within the ear canal 1804,
additional techniques for using acquired data will now be described.

[0227] FIG. 19 depicts a user interface for earpiece design/selection
using dynamic data as contemplated herein. In general, the user interface
1900 may include a depiction of an ear canal based upon three-dimensional
data captured as described above. The interface may generally show an
image 1902 including a shape of the ear canal 1904 in cross-section or
other two-dimensional or three-dimensional view based upon capture shape
data. The image 1902 may be color-coded or annotated with quantitative
values reflecting elasticity, hardness, or the like around an inner wall
1906 of the ear canal, or inferred tissue structure such as bone,
cartilage, or the like may be displayed.

[0228] In general, the user interface 1900 may include navigation controls
1908 for panning, zooming, rotating, or otherwise manipulating the
perspective of the view of the ear canal 1904 and surrounding spatial
data. Further, any number of controls such as buttons, sliders, text
fields, and the like may be included to assist a user in an earpiece
design or selection process. This may, for example, include a first
control 1912 to auto-select an earpiece. A second control 1914 may permit
manual selection or sizing of an earpiece. A third control 1916 may
permit acoustic testing based upon, e.g., a simulation of an acoustic
chamber 1918 formed within the ear canal 1904. A fourth control 1920 may
permit sizing or movement of a selected earpiece 1922 within the ear
canal 1904. A fifth control 1924 may permit selection of a
musculoskeletal movement and/or animated display of corresponding shape
changes to the ear canal 1904. More generally any useful control or group
of controls may be included within the user interface 1900 to assist a
user in an automated, semi-automated, or manually design process using
dynamic data such as compliance data or shape change data as generally
contemplated herein.

[0229] It will be understood that the imaging system described herein may
only obtain detailed three-dimensional data from portions of the ear
canal. Thus the user interface may augment the captured data with a
stylized or abstract ear, tympanic membrane, and so forth to provide a
user with appropriate context. Alternatively, this ancillary data may be
omitted from the user interface, or actual three-dimensional data may be
captured form a user's outer ear, head, and the like to provide a more
accurate contextual depiction within the user interface.

[0230] FIG. 20 is a flowchart of a method 2000 for earpiece selection
using dynamic data. In general, dynamic data may be used to identify soft
tissue, bone, cartilage, and the like that forms an inner wall of an ear
canal or other cavity, and shape data may more generally characterize ear
canal shape, an acoustic chamber formed by placement of an earpiece, and
other features of the ear canal such as location of the tympanic
membrane, all as described above. This data may be usefully employed to
determine the size and shape of an earpiece such as a hearing aid, or to
select one of a number of pre-fabricated hearing aids, or shells for
hearing aids, that best fit the ear, taking into account aspects of the
ear canal such as size and shape. In addition, the earpiece may be
designed or selected so that the earpiece is suitably oversized for a
secure fit where there is soft tissue within the ear canal, or undersized
to avoid discomfort around bone or other hard tissue.

[0231] As shown in step 2002, the method 1900 may include providing a
library of earpieces that includes three-dimensional shape data for a
plurality of preexisting earpiece types. A variety of earpiece types are
known, include behind-the-ear (BTE), mini behind-the-ear (mini-BTE),
in-the-ear (ITE), in-the-canal (ITC), and completely-in-canal (CIC). Each
type may have one or more shapes or sizes, which may be adapted for
insertion or provided as a shell over which a customized mold for a
patient may be designed and added. The library may include other
information concerning acoustics, microphone placement, feature or
hardware specifications, and so forth. While the earpieces may include
hearing aids such as those described above, it will further be
appreciated that the earpieces may be other earpiece types or
subassemblies. For example, the earpieces may include earbuds for audio
players, or the earpieces may include earpiece bodies for use with
personalized molds that are customized for individual users.

[0232] As shown in step 2004, the method 2000 may include obtaining
dynamic data from an ear canal of a subject as generally described above.
The dynamic data may more specifically include data from the ear canal
characterizing changes in a shape of the ear canal related to at least
one of a compliance of the ear canal to changes in pressurization or a
shape change of the ear canal in response to a musculoskeletal movement
of a head of the subject.

[0233] As shown in step 2006, the method may include obtaining static data
from the ear canal of the subject, the static data including a
three-dimensional representation of a surface of the ear canal. The
static data may be used, for example, to size an earpiece, and to provide
a three-dimensional shape of the ear canal for display in a user
interface.

[0234] As shown in step 2008, the method 2000 may include selecting one of
the plurality of preexisting earpiece types from the library that
provides a best fit to the ear canal based on the dynamic data, thereby
providing a selected type. A variety of techniques for making this
selection are available. This may include automated selection based on
geometric comparison, filtering based on the ability of the ear canal to
yield to an inserted device based on, e.g., the dynamic data, and so
forth. The parameters for fitting an earpiece to an ear canal are well
known in the art, and are not described here in detail except by way of
illustrative example. A user interface as illustrated above may be
provided in a computerized system to permit a user to manually compare
fits of various devices. In general, the selection may account for
volumetric constraints (actual fit of device components (battery,
speaker, processor, microphone, vent tubes, etc.)), positioning
constraints (suitable location relative to tympanic membrane), and so
forth. For example, Invisible-In-The-Canal (IIC) hearing aids impose
specific size requirements on the ear canal near the tympanic membrane,
which geometric features may be directly viewed by a user within the user
interface, or automatically analyzed for appropriateness of an IIC based
upon three-dimensional shape data.

[0235] Selecting an earpiece may additionally include making an initial
selection of one of the plurality of preexisting earpiece types from the
library based upon the static data, and evaluating a fit of the one of
the plurality of preexisting earpiece types based on the dynamic data.
This evaluation may include a spatial test fit of the earpiece to the ear
canal, as well as simulation of acoustics within the acoustic chamber and
any other useful evaluations relating to comfort of the earpiece for the
user, performance of the earpiece, and so forth.

[0236] As shown in step 2010, the method 2000 may include creating a
digital design for a personalized mold that is shaped and sized for the
ear canal of the subject. For certain earpieces, a standard body is
customized for an individual with a personalized shell or covering. When
such an earpiece is selected, the design process may include generating a
three-dimensional design for the shell based upon the geometry of the
standard body and the geometry of the ear canal, as obtained using the
inflatable membrane described above. In such circumstances the standard
body and customized shell may be displayed within a user interface and
simulated or otherwise tested for fit over a range of motion. In
addition, data such as compression of the shell (which may be oversized
to the ear canal) may be estimated and adjusted by a user for improved
seal, comfort, or the like.

[0237] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 20
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 2000.

[0238] FIG. 21 is a flowchart of a method 2100 for creating a material
profile to fabricate an earpiece. In general, the shape of an ear canal
and the relative elasticity of tissue surrounding the ear canal may
suggest materials having different stiffness or elasticity. In addition,
different modes of deformation for an earpiece may be suggested by, for
example, the insertion/removal path for the earpiece, the position of an
acoustic seal, and so forth. The material profiles described below may
accommodate any one or more of these physical constraints on earpiece
design and use, and may be applied to select from preexisting earpieces
or to specify materials for a custom-fabricated earpiece.

[0239] As shown in step 2102, the method 2100 may begin with providing a
library of a plurality material types available for use in a fabrication
process, each of the plurality of material types characterized by
elasticity. Each material may be further characterized by any of a number
of additional parameters such as strength, durability, comfort, cost,
acoustic properties, and the like, including without limitation any
parameter that might be used to evaluate the material's suitability for a
particular object to be fabricated. For example, each material may
characterized by at least one of a bulk modulus, a modulus of elasticity,
and a compressibility. These properties may be used to simulate a static
fit, and to evaluate whether and how the fit is maintained as the ear
canal changes shape over time (e.g., in response to musculoskeletal
movements). Similarly, each material may be characterized by two or more
elastic moduli, e.g., along orthogonal axes, or any other mechanical
properties such as viscoelastic properties. The library may be stored in
a database or any other suitable non-transitory medium.

[0240] As shown in step 2104, the method 2100 may include obtaining static
data from an ear canal of a subject, the static data including a
three-dimensional image of a surface of the ear canal at a predetermined
pressure. This may include image capture using any of the systems and
methods described above.

[0241] As shown in step 2106, the method 2100 may include obtaining
dynamic data from the ear canal of the subject, the dynamic data
including data from the ear canal characterizing changes in a shape of
the ear canal related to at least one of a compliance of the ear canal to
changes in pressurization or a shape change of the ear canal in response
to a musculoskeletal movement of a head of the subject. This may more
generally include any dynamic data captured using the systems and methods
described above.

[0242] As shown in step 2108, the method 2100 may include calculating a
shape for an earpiece based upon the static data. In general, this
includes matching an earpiece to the geometry of the ear canal, taking
into account insertion and removal, an acoustic seal and the formation of
an acoustic chamber adjacent to a tympanic membrane, oversize for secure
fit, undersizing for comfort, placement of earpiece hardware and vents,
and so forth. For example, the ear canal may narrow in response to
certain musculoskeletal movements such as when the mouth opens. In
addition to selecting a softer material for these regions, the earpiece
may be undersized, or alternatively, undersized relative to a standard
oversizing margin, to more readily accommodate these anticipated shape
changes during use. In one aspect, calculating earpiece shape may involve
fitting to geometry of the ear canal, the outer ear, and so forth.

[0243] This may include oversizing the earpiece relative to the ear canal
by a predetermined amount (e.g. 10% by volume or by linear dimension)
throughout the earpiece. The predetermined amount may be varied according
to the dynamic data, e.g., by oversizing more in areas of greater
elasticity (of the ear canal wall) and oversizing less in areas where the
ear canal wall is harder, such as near bone or other hard tissue. More
generally, oversizing may include varying the amount of oversizing in
different regions of the earpiece. In another aspect, this may include
adapting the shape and size using known principles of earpiece design to
achieve an earpiece that securely fits within the ear canal, is
comfortable for a user, and provides good acoustic performance. The
predetermined amount of oversizing may also be determined in part by the
hearing loss profile of an intended user. For example, people with large
hearing loss typically require large gain in amplification, which
increases the chance of feedback squeal if an air gap opens up between
the speaker and microphone. In such a context, there may be more
oversizing to prevent adverse acoustic consequences, even if this comes
at the expense of patient comfort.

[0244] As shown in step 2110, the method 2100 may include calculating a
material profile for the earpiece based upon the dynamic data using one
or more of the plurality of material types of the library. That is, given
the shape determined in step 2108, along with information about fit and
use of the earpiece derived from the dynamic data, suitable materials may
be selected for fabrication of an earpiece having the desired shape and
desired physical and mechanical properties. It will be appreciated that
determination of a material profile may be performed concurrently with
the shape determination of step 2108, or after the earpiece shape is
determined, or iteratively such as where shape and material profile are
alternately adjusted to converge on a final shape and material profile.

[0245] As shown in step 2112, the method 2100 may include converting the
shape and the material profile into an earpiece design for use by a rapid
fabrication system. In such a design, each of the plurality of material
types may be selected from materials available in a rapid fabrication
process, or multiple rapid fabrication processes, so that the resulting
shape and material profile can be readily converted into suitable tool
instructions.

[0246] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 21
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 2100.

[0247] FIG. 22 is a flowchart of a method for simulation of dynamic fit
and acoustics for an earpiece. In generally, the dynamic data and static
data for an ear canal, as captured using the systems and methods
disclosed above, may be used to simulate an earpiece placed for use in an
end user's ear canal, and to thereby improve design prior to fabrication
of the earpiece.

[0248] As shown in step 2202, the method 2200 may begin with obtaining
static data from an ear canal of a subject, the static data including a
three-dimensional image of a surface of the ear canal at a predetermined
pressure. This may include a scan of ear canal shape using an inflatable
membrane as described above. It will be appreciated that the `static`
image may be obtained under pulsating or otherwise varying pressure as
generally discussed above. As such, the term static as used to describe
image data does not necessarily imply static imaging conditions, but
rather is intended to describe the capture of a fixed three-dimensional
shape, in contrast to dynamic data which captures shape variations under
time-changing conditions.

[0249] As shown in step 2204, the method 2200 may include obtaining
dynamic data from the ear canal of the subject, the dynamic data
including data from the ear canal characterizing changes in a shape of
the ear canal related to a compliance of the ear canal to changes in
pressurization and a shape change of the ear canal in response to a
musculoskeletal movement of a head of the subject. The compliance data
may be used, for example, to model acoustic behavior of the ear canal
walls, or to how the ear canal wall will yield (or conversely how an
earpiece will yield) when an earpiece is placed for use therein.

[0250] As shown in step 2206, the method may include providing a
three-dimensional model of an earpiece. It will be understood that this
may be a complete physical model including a complete characterization of
exterior surfaces of the earpiece, or this may include other information
such as overall sizing limits or the shape and/or size of individual
components (circuitry, battery, speaker, microphone, etc.) that must be
included in the earpiece, from which a specific or generalized shape and
size may be determined.

[0251] As shown in step 2208, the method may include simulating a fit of
the three-dimensional model of the earpiece to the ear canal based on the
static data and the dynamic data, thereby providing a simulation result.
It will be understood that given a static and dynamic model of an ear
canal, as captured using the methods and systems disclosed herein, along
with a physical model of an earpiece, a variety of simulations may be
performed. This may generally include physical simulation of earpiece
fit, as well as various acoustic properties based upon, e.g., the shape
of the acoustic chamber formed within the ear canal and the properties of
the ear canal walls as determined by the dynamic data.

[0252] In another aspect, step 2208 may include simulating an acoustic
response of a chamber formed when the earpiece is placed in the ear canal
based on the static data and the dynamic data. The acoustic response may
depend on placement of various acoustic components. As such, the
simulation may include selecting a location for a placement of a speaker
in the earpiece based upon the acoustic response. Where speaker location
has been satisfactorily simulated, the subsequent design/evaluation steps
may include positioning the speaker in a desired location within an
earpiece model for fabrication or creating a digital model for
fabrication of an earpiece that includes the speaker placed at the
location. Other simulations may also or instead be performed. For
example, the method 2200 may include evaluating an integrity of an
acoustic seal for the chamber formed by the earpiece based upon the shape
change of the ear canal in response to the musculoskeletal movement of
the head, acoustically simulating a microphone for the earpiece, or
optimizing vent placement for the earpiece.

[0253] As shown in step 2210, the method may include evaluating a
suitability of the earpiece for the ear canal based upon the simulation
result. Suitability may be based on one or more of a variety of criteria.
For example, suitability may be evaluated based on the characteristics of
an acoustic chamber formed within the ear canal by the earpiece, or the
quality of an acoustic seal formed by the earpiece when placed for use in
the ear canal. This determination may rely for example on the acoustic
properties of the ear canal wall as determined from the dynamic data. As
another example, suitability may be evaluated based on the nature of the
physical fit between an earpiece and the ear canal. Thus for example, if
air gaps form between the earpiece and the ear canal wall during various
musculoskeletal movements, the earpiece model or design may be rejected
as unsuitable. Similarly, if excessive pressure is exerted against the
ear canal when the earpiece is inserted, this may result in user
discomfort that would render the earpiece unsuitable. Thus in one aspect
evaluating suitability may include estimating a comfort of the earpiece
for a subject, more specifically the subject from which the static and
dynamic ear canal data was obtained.

[0254] As shown in step 2212, the method 2200 may include providing design
guidance based upon the simulation and evaluation. This may, for example,
include modifying the three-dimensional model of the earpiece based upon
the simulation result (or suggesting modifications for manual entry by a
user). This may also or instead include selecting one of a plurality of
pre-fabricated earpieces corresponding to the three-dimensional model for
use by the subject based upon the simulation result, thereby providing a
selection, or suggesting one such earpiece for manual selection by a
user. Where the selection is automated, the selection may be displayed in
a user interface or the like for review by a user. This may also or
instead include fabricating an earpiece based upon the three-dimensional
model, or otherwise providing fabrication instructions based upon the
model.

[0255] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 22
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 2200.

[0256] FIG. 23 is a flowchart of a method for positioning control inputs
in an earpiece. As noted above, the three-dimensional imaging techniques
described above permit measurement of ear canal shape change that can be
correlated to musculoskeletal movements of a subject. Using this data,
areas of maximum deflection of an ear canal can be identified and inputs
can be positioned at complementary locations on an earpiece to detect,
e.g., a yawn, a sidewise jaw movement, or any other motion or combination
of motions that result in shape change within the ear canal. The earpiece
may then be programmed to respond to such movements, thus permitting
hands-free control of the earpiece with properly orchestrated
musculoskeletal movements. By way of non-limiting example, a user may
raise both eyebrows to mute a speaker in an earpiece or turn the head
from side to side to increase the volume. More generally, any detectable
input may be used to control any controllable feature of the earpiece
based upon the techniques described below.

[0257] As shown in step 2302, the method 2300 may begin with obtaining
static data from an ear canal of a subject, the static data including a
three-dimensional image of a surface of the ear canal at a predetermined
pressure.

[0258] As shown in step 2304, the method 2300 may include obtaining
dynamic data from the ear canal of the subject, the dynamic data
including data from the ear canal characterizing a shape change of the
ear canal in response to a musculoskeletal movement of a head of the
subject.

[0259] As shown in step 2306, the method 2300 may include correlating the
shape change to the musculoskeletal movement to identify a surface region
of the ear canal where the shape change due to the musculoskeletal
movement meets or exceeds a predetermined threshold. It will be
understood that the predetermined threshold may be any of a variety of
relative or absolute thresholds. For example, a relative threshold may be
a percentage change in position relative to an overall dimension or
relative to other surface points on an ear canal. The threshold may also
or instead include an absolute threshold such as a minimum or maximum
surface displacement or an average surface displacement measured, e.g.,
over the duration of a musculoskeletal movement. In another aspect, the
predetermined threshold may be a time-varying displacement. Thus for
example, when a particular word is spoken (or the corresponding jaw, lip,
and tongue movements made), the ear canal may exhibit a time-varying
shape change with various minima and maxima at various locations. A
particular displacement pattern at a particular location may serve as a
threshold for detection of a corresponding musculoskeletal movement
regardless of overall regions of maximum displacement.

[0260] As shown in step 2308, the method 2300 may include providing an
earpiece design including a three-dimensional model of an earpiece fitted
to the ear canal based upon the static data.

[0261] As shown in step 2310, the method 2300 may include positioning an
input transducer in the earpiece design in a location corresponding to
the surface region of the ear canal where the shape change due to the
musculoskeletal movement meets or exceeds a predetermined threshold when
the earpiece is placed for use in the ear canal. It will be understood
that a variety of input transducers may be employed including without
limitation optical switches, hall effect switches, motion detection
switches, inertial switches, pressure-sensitive switches, and so forth.
The step of position the input transducer may be aided by displaying
within a user interface areas of the ear canal that exhibit a substantial
shape change in response to the musculoskeletal movement and permitting a
user to manually position the input transducer, which may be color-coded
or otherwise annotated to indicate magnitude of displacement. This may,
for example, include displaying an amount of shape change at one or more
surface regions of the ear canal in response to the musculoskeletal
movement, such as with textual, numeric, or color-coded annotations. It
should further be appreciated that the musculoskeletal movement may be a
time-varying movement over a period of time. For example, the movement
may include saying a word such as `mute`, which may create a
correspondingly time-varying predetermined threshold rather than a static
measurement of when a positional limit has been exceeded.

[0262] As shown in step 2312, the method 2300 may include fabricating an
earpiece with an input transducer positioned according to the design of
step 2310. It will be appreciated that fabricating an earpiece may
include any number of additional fabrication steps known to one of skill
in the art, such as coupling the input transducer to control circuitry
for the earpiece, such as a volume control, mute control, power control,
and so forth. Where the earpiece is an earbud for an audio player, the
input transducer may also or instead usefully control track selection
playback start and stop, and so forth.

[0263] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 23
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 2300.

[0264] FIG. 24 shows an earpiece designed according to the method of FIG.
23. In general, the earpiece 2400 may include a transducer 2402, a
processor 2404, a microphone 2406, and a speaker 2408. The earpiece 2400
may be shaped and sized for an ear canal of a subject. The transducer
2402 may be any transducer sensitive to pressure, either directly (as in
a pressure sensitive switch) or indirectly (as in a motion or distance
detection sensor).

[0265] In general, the transducer 2402 may be positioned within the
earpiece at a position that, when the earpiece 2400 is placed for use in
the ear canal, corresponds to a location on a surface of the ear canal
that exhibits a substantial shape change correlated to a musculoskeletal
movement of the subject. The position depicted in FIG. 24 is provided by
way of example only, and it will be understood that any position
exhibiting substantial displacement may be used to position the
transducer 2402 for use as contemplated herein. In one aspect, the
transducer 2402 may be positioned at a position that, when the earpiece
is placed for use in the ear canal, corresponds to a location on a
surface of the ear canal that exhibits a maximum surface displacement
from a neutral position in response to the musculoskeletal movement of
the subject. In another aspect, the transducer 2402 may be positioned at
a position that, when the earpiece is placed for use in the ear canal,
corresponds to a location on a surface of the ear canal that exceeds an
average surface displacement from a neutral position in response to the
musculoskeletal movement of the subject. It will be understood that,
while a single transducer 2402 is depicted, a number of transducers may
be included, which may detect different musculoskeletal movements, or may
be coordinated to more accurately detect a single musculoskeletal
movement.

[0266] The processor 2404 may be coupled to the microphone 2406, speaker
2408, and transducer 2402, and may be configured to detect the
musculoskeletal movement of the subject based upon a pressure change
signal from the transducer 2402, and to generate a predetermined control
signal in response to the musculoskeletal movement. The predetermined
control signal may, for example, be a mute signal for the earpiece, a
volume change signal for the earpiece, or, where the earpiece is an
earbud for an audio player (in which case the microphone 2406 may
optionally be omitted), a track change signal for the audio player
coupled to the earpiece. In one aspect, the FIG. 25 is a flowchart of a
method for using dynamic ear canal data for medical diagnosis. In
general, the systems and methods disclosed herein permit quick and
accurate capture of ear canal data over a range of pressurizations and/or
a range of musculoskeletal movements. Where this generally dynamic
behavior of the ear canal can be correlated to particular medical
conditions, a dynamic data ear canal scanner may be configured as a
diagnostic tool for detection of those conditions.

[0267] As shown in step 2502, the method 2500 may begin by obtaining
dynamic data from a plurality of ear canals of a plurality of subjects,
the dynamic data for each of the ear canals including data from the ear
canal characterizing a change in a shape of the ear canal related to at
least one of a compliance of the ear canal to changes in pressurization
or a shape change of the ear canal in response to a musculoskeletal
movement of a head of a corresponding one of the subjects, wherein some
of the subjects have been diagnosed with a medical condition. It will be
understood that static data may also be obtained from a plurality of ear
canals of a plurality of subjects, including three-dimensional images of
the ear canal at a predetermined pressure. This static data may be used,
for example, as a baseline for identifying surface displacements in the
dynamic data relative to the static data.

[0268] Obtaining dynamic data may include obtaining data using any of the
methods and systems described above. Thus for example, obtaining dynamic
data may include, for each one of the plurality of ear canals of the
plurality of subjects, inflating an inflatable membrane within the ear
canal so that the inflatable membrane conforms to an inner surface of the
ear canal and capturing a plurality of distance measurements from a
sensor within the inflatable membrane to a surface of the inflatable
membrane, thereby providing a three-dimensional image of the inflatable
membrane in a shape that is conformed to the ear canal.

[0269] As shown in step 2504, the dynamic data may be analyzed to identify
a correlation between the medical condition and the dynamic data for the
ones of the subjects that have been diagnosed with the medical condition.
The techniques for such correlation are well known in the art and are not
described here in detail, except to note that the strength of or
statistical confidence in a correlation may affect the diagnostic
significance ascribed to a particular match based upon the correlation.

[0270] As shown in step 2506, the correlation, where identified may
subsequently be used as a predictor for the medical condition. Thus in
one aspect there is disclosed herein a diagnostic method and system based
upon dynamic ear canal data, which may be captured using any of the
imaging systems and methods described above. It will be readily
appreciated that any body cavity amenable to dynamic data capture may be
similarly obtained for a population and used to identify correlations
with diagnostic significance.

[0271] As shown in step 2508, the method may include obtaining second
dynamic data from an ear canal of an undiagnosed subject and calculating
a likelihood that the undiagnosed subject has the medical condition based
upon the correlation. This may obtained using any of the techniques
described above. Thus for example obtaining second dynamic data may
include inflating an inflatable membrane within the ear canal of an
undiagnosed subject so that the inflatable membrane conforms to an inner
surface of the ear canal and capturing a plurality of distance
measurements from a sensor within the inflatable membrane to a surface of
the inflatable membrane, thereby providing a three-dimensional image of
the inflatable membrane in a shape that is conformed to the ear canal.

[0272] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 25
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 2500.
Thus in one aspect there is disclosed herein a diagnostic tool for
performing diagnoses based upon a capture of static and dynamic data from
an ear canal of an undiagnosed subject.

[0273] FIG. 26 is a flowchart of a method for fitting an earpiece using
dynamic data.

[0274] As shown in step 2602, the method 2600 may begin with obtaining
static data from an ear canal of a subject, the static data including a
three-dimensional image of a surface of the ear canal at a predetermined
pressure.

[0275] As shown in step 2604, the method 2600 may include obtaining
dynamic data from the ear canal of the subject, the dynamic data
including data from the ear canal characterizing changes in a shape of
the ear canal related to a compliance of the ear canal to changes in
pressurization and a shape change of the ear canal in response to a
musculoskeletal movement of a head of the subject.

[0276] As shown in step 2606, the method may include providing a
three-dimensional model of an earpiece, such as any of the
three-dimensional models described above.

[0277] As shown in step 2608, the method 2600 may include evaluating a fit
of the three-dimensional model of the earpiece to the ear canal based on
the static data and the dynamic data. This may include any of the fit or
simulation tests described above to determine a quality and comfort of
the modeled earpiece in the measured ear canal. For example, this may
include evaluating the fit according to pressure applied by the earpiece
to the ear canal. This may also or instead include evaluating the fit
according to the size of the earpiece relative to the size of the ear
canal in one or more regions of low compliance, that is, regions where
the ear canal does not yield to the earpiece (e.g., regions with
substantial adjacent bone or cartilage). This may also or instead include
valuating the fit according to an acoustic seal of the earpiece, or
evaluating the fit to identify one or more deformation modes of the
earpiece when placed for use in the ear canal. For example, where the ear
canal exhibits substantial curvature, the earpiece may need substantial
axial flexibility for insertion and removal. Thus the one or more
deformation modes may include deformation during insertion of the removal
of the earpiece. This may also or instead include deformation modes
caused by a shape change of the ear canal in response to musculoskeletal
movement of the head of the subject, or deformation modes induced by the
relative stiffness and shape of the earpiece and/or ear canal.

[0278] As shown in step 2610, the method 2600 may include modifying a
characteristic of the three-dimensional model to improve the fit. This
may include modifying a shell for an earpiece, modifying a shape of the
earpiece, selecting different (e.g., firmer or softer) materials for
fabrication of the earpiece or otherwise modifying a material profile of
the three dimensional model, and so forth. Modifying the characteristic
may also or instead include positioning an articulating joint within the
three-dimensional model, e.g., to accommodate axial deformation during
insertion/removal of the earpiece. Modifying the characteristic may also
or instead include modifying an elasticity of a portion of the
three-dimensional model.

[0279] It will further be appreciated that, based on the compliance data
captured during a scan, a good estimate can be obtained of the maximum
short-duration expansion of regions of the ear canal. This data may be
useful for modeling the insertion and removal of the earpiece, and
modifying the earpiece design accordingly to reduce discomfort during
insertion and removal of the earpiece.

[0280] It will be readily appreciated that a device such as any of the
devices described above may be adapted to perform the method of FIG. 26
with suitable programming or other configuration of the processor and/or
other processing circuitry. Also disclosed herein is a computer program
product comprising computer executable code embodied in a non-transitory
computer readable medium that, when executing on one or more computing
devices, performs the processing steps associated with the method 2600.

[0281] It will be appreciated that any of the above systems, devices,
methods, processes, and the like may be realized in hardware, software,
or any combination of these suitable for the control, data acquisition,
and data processing described herein. This includes realization in one or
more microprocessors, microcontrollers, embedded microcontrollers,
programmable digital signal processors or other programmable devices,
along with internal and/or external memory. This may also, or instead,
include one or more application specific integrated circuits,
programmable gate arrays, programmable array logic components, or any
other device or devices that may be configured to process electronic
signals. It will further be appreciated that a realization of the
processes or devices described above may include computer-executable code
created using a structured programming language such as C, an object
oriented programming language such as C++, or any other high-level or
low-level programming language (including assembly languages, hardware
description languages, and database programming languages and
technologies) that may be stored, compiled or interpreted to run on one
of the above devices, as well as heterogeneous combinations of
processors, processor architectures, or combinations of different
hardware and software. At the same time, processing may be distributed
across devices such as a camera and/or computer and/or server or other
remote processing resource in a number of ways, or all of the
functionality may be integrated into a dedicated, standalone device. All
such permutations and combinations are intended to fall within the scope
of the present disclosure.

[0282] In other embodiments, disclosed herein are computer program
products comprising computer-executable code or computer-usable code
that, when executing on one or more computing devices, performs any
and/or all of the steps described above. The code may be stored in a
computer memory, which may be a memory from which the program executes
(such as random access memory associated with a processor), or a storage
device such as a disk drive, flash memory or any other optical,
electromagnetic, magnetic, infrared or other device or combination of
devices. In another aspect, any of the processes described above may be
embodied in any suitable transmission or propagation medium carrying the
computer-executable code described above and/or any inputs or outputs
from same.

[0283] While the invention has been disclosed in connection with the
preferred embodiments shown and described in detail, various
modifications and improvements thereon will become readily apparent to
those skilled in the art. Accordingly, the spirit and scope of the
present invention is not to be limited by the foregoing examples, but is
to be understood in the broadest sense allowable by law.